warden_server/README

@@ -42,13 +42,13 @@ B. Dependencies
 
  2. Python modules
 
-    python-mysqldb 5.3.3+
+    python-mysqldb 5.3.3+ | python-psycopg2 2.8.6+
     python-m2crypto 0.20+
     jsonschema 2.4+
 
  3. Database
 
-    MySQL | MariaDB >= 5.5
+    MySQL | MariaDB >= 5.5 | PostgreSQL >= 13
 
 ------------------------------------------------------------------------------
 C. Installation
@@ -70,14 +70,28 @@ C. Installation
    > GRANT ALL ON warden3.* TO `warden`@`localhost`;
    > FLUSH PRIVILEGES;
 
+   # psql
+
+   > CREATE DATABASE warden3 ENCODING 'UTF-8';
+   > CREATE ROLE "warden" LOGIN PASSWORD 'example';
+   > GRANT ALL ON DATABASE "warden3" TO "warden";
+
  * Create necessary table structure
 
-   mysql -p -u warden warden3 < warden_3.0.sql
+   mysql -p -u warden warden3 < warden_3.0_mysql.sql
+
+   or
+
+   psql -U warden -h localhost warden3 < warden_3.0_postgres.sql
 
  * Get up to date Idea schema
 
    wget -O warden_server/idea.schema https://idea.cesnet.cz/_media/en/idea0.schema
 
+ * Load category and tag maps into database (This step is optional for MySQL dbms)
+
+   ./warden_server.py loadmaps
+
  * Enable mod_wsgi, mod_ssl, include Warden configuration
 
    This depends heavily on your distribution and Apache configuration.
@@ -129,7 +143,7 @@ particular implementation object of the aspect, for example type of logger
    Sections and their "type" objects can be:
 
 		Log: FileLogger, SysLogger
-		DB: MySQL
+		DB: MySQL, PostgreSQL
 		Auth: X509Authenticator, X509NameAuthenticator,
               X509MixMatchAuthenticator,PlainAuthenticator
 		Validator: JSONSchemaValidator, NoValidator
@@ -186,22 +200,36 @@ object from particular section list is used ("FileLogger" for example).
       retry_count: number of retries, defaults to 3
       event_size_limit: max size of serialized event, defaults to 5 MB
       catmap_filename: IDEA category mapping to database ids, defaults to
-                       "catmap_mysql.json" at installation directory
+                       "catmap_db.json" at installation directory
+      tagmap_filename": IDEA node type mapping to database ids, defaults to
+                        "tagmap_db.json" at installation directory
+
+   PostgreSQL: database storage backend
+      host: database server host, default "localhost"
+      user: database user, default "warden"
+      password: database password
+      dbname: database name, default "warden3"
+      port: database server port, default 5432
+      retry_pause: retry in case of database errors, in seconds, defaults to 5
+      retry_count: number of retries, defaults to 3
+      event_size_limit: max size of serialized event, defaults to 5 MB
+      catmap_filename: IDEA category mapping to database ids, defaults to
+                       "catmap_db.json" at installation directory
       tagmap_filename": IDEA node type mapping to database ids, defaults to
-                        "tagmap_mysql.json" at installation directory
+                        "tagmap_db.json" at installation directory
 
    WardenHandler: Main Warden RPC worker
       send_events_limit: max events sent in one bunch, defaults to 10000
       get_events_limit: max events received in one bunch, defaults to 10000
       description: human readable description, sent in server info
-	
+
 ------------------------------------------------------------------------------
 E. Command line
 
    When run from command line, server offers set of commands and options for
 runtime and database management. You can also use --help option for each
 command and for server itself.
-   
+
 warden_server.py [--help] [-c CONFIG] <command>
 
 optional arguments:
@@ -285,11 +313,9 @@ warden_server.py purge [--help] [-l] [-e] [-d DAYS]
 
 warden_server.py loadmaps [--help]
 
-   Load 'categories' and 'tags' table from 'catmap_mysql.json' and
-   'tagmap_mysql.json'. Note that this is NOT needed for server at all, load
-   them into db at will, should you need to run your own specific SQL queries
-   on data directly. Note also that previous content of both tables will be
-   lost.
+   Load 'categories' and 'tags' table from 'catmap_db.json' and
+   'tagmap_db.json'. Note also that previous content of both tables
+   will be lost.
 
 ------------------------------------------------------------------------------
 Copyright (C) 2011-2015 Cesnet z.s.p.o

warden_server/test_warden_server.py

@@ -39,7 +39,7 @@ def setUpModule():      # pylint: disable = locally-disabled, invalid-name
             cur.execute("DROP DATABASE IF EXISTS %s" % (DB,))   # NOT SECURE
             cur.execute("CREATE DATABASE %s" % (DB,))           # NOT SECURE
             cur.execute("USE %s" % (DB,))                       # NOT SECURE
-            with open(path.join(path.dirname(__file__), 'warden_3.0.sql')) as script:
+            with open(path.join(path.dirname(__file__), 'warden_3.0_mysql.sql')) as script:
                 statements = ''.join([line.replace('\n', '') for line in script if line[0:2] != '--']).split(';')[:-1]
                 for statement in statements:
                     cur.execute(statement)

warden_server/warden_3.0_postgres.sql

+SET TimeZone='+00:00';
+
+CREATE COLLATION case_insensitive (
+  provider = icu,
+  locale = 'und-u-ks-level2',
+  deterministic = false
+);
+
+-- ---------------------------------------------------------
+
+--
+-- Database: "warden3"
+--
+
+-- --------------------------------------------------------
+
+--
+-- Table structure for table "categories"
+--
+
+CREATE TABLE "categories" (
+  "id" int NOT NULL UNIQUE CHECK ("id" >= 0),
+  "category" text NOT NULL COLLATE case_insensitive,
+  "subcategory" text DEFAULT NULL COLLATE case_insensitive,
+  "cat_subcat" text NOT NULL COLLATE case_insensitive
+);
+
+CREATE INDEX "cat_sub" ON "categories" ("cat_subcat");
+
+-- --------------------------------------------------------
+
+--
+-- Table structure for table "clients"
+--
+
+CREATE TABLE "clients" (
+  "id" SERIAL PRIMARY KEY,
+  "registered" timestamp NOT NULL DEFAULT '1970-01-01 00:00:00',
+  "requestor" text NOT NULL COLLATE case_insensitive,
+  "hostname" text NOT NULL COLLATE case_insensitive,
+  "note" text NULL COLLATE case_insensitive,
+  "valid" smallint NOT NULL DEFAULT '1' CHECK ("valid" >= 0),
+  "name" text NOT NULL,
+  "secret" text NULL,
+  "read" smallint NOT NULL DEFAULT '1' CHECK ("read" >= 0),
+  "debug" smallint NOT NULL DEFAULT '0' CHECK ("debug" >= 0),
+  "write" smallint NOT NULL DEFAULT '0' CHECK ("write" >= 0),
+  "test" smallint NOT NULL DEFAULT '0' CHECK ("test" >= 0)
+);
+
+CREATE INDEX "clients_1" ON "clients" ("valid", "secret", "hostname");
+CREATE INDEX "clients_2" ON "clients" ("valid", "name");
+
+-- --------------------------------------------------------
+
+--
+-- Table structure for table "events"
+--
+
+CREATE TABLE "events" (
+  "id" BIGSERIAL PRIMARY KEY,
+  "received" timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  "client_id" int NOT NULL REFERENCES "clients" ("id"),
+  "data" bytea NOT NULL,
+  "valid" smallint NOT NULL DEFAULT '1' CHECK ("valid" >= 0)
+);
+
+CREATE INDEX "id" ON "events" ("id", "client_id");
+CREATE INDEX "received" ON "events" ("received");
+
+SELECT nextval('events_id_seq'); -- AUTO_INCREMENT = 2
+
+-- --------------------------------------------------------
+
+--
+-- Table structure for table "event_category_mapping"
+--
+
+CREATE TABLE "event_category_mapping" (
+  "event_id" bigint NOT NULL REFERENCES "events" ("id") ON DELETE CASCADE,
+  "category_id" int NOT NULL,
+  PRIMARY KEY ("event_id", "category_id"),
+  CONSTRAINT "event_category_mapping_category_id_fk" FOREIGN KEY ("category_id") REFERENCES "categories" ("id")
+);
+
+
+-- --------------------------------------------------------
+
+--
+-- Table structure for table "last_events"
+--
+
+CREATE TABLE "last_events" (
+  "id" SERIAL PRIMARY KEY,
+  "client_id" int NOT NULL REFERENCES "clients" ("id"),
+  "event_id" bigint REFERENCES "events" ("id"),
+  "timestamp" timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE INDEX "client_id" ON "last_events" ("client_id", "event_id");
+
+-- --------------------------------------------------------
+
+--
+-- Table structure for table "tags"
+--
+
+CREATE TABLE "tags" (
+  "id" int NOT NULL UNIQUE CHECK ("id" >= 0),
+  "tag" text NOT NULL COLLATE case_insensitive
+);
+
+CREATE INDEX "id_tag_name" ON "tags" ("id", "tag");
+CREATE INDEX "tag_name" ON "tags" ("tag");
+
+-- --------------------------------------------------------
+
+--
+-- Table structure for table "event_tag_mapping"
+--
+
+CREATE TABLE "event_tag_mapping" (
+  "event_id" bigint NOT NULL REFERENCES "events" ("id") ON DELETE CASCADE,
+  "tag_id" int NOT NULL,
+  PRIMARY KEY ("event_id", "tag_id"),
+  CONSTRAINT "event_tag_mapping_tag_id_fk" FOREIGN KEY ("tag_id") REFERENCES "tags" ("id")
+);

warden_server/warden_server.py

@@ -16,11 +16,10 @@ import json
 import re
 from traceback import format_tb
 from collections import namedtuple
+from itertools import repeat
 from time import sleep
 from random import randint
 import M2Crypto.X509
-import MySQLdb as my
-import MySQLdb.cursors as mycursors
 
 if sys.version_info[0] >= 3:
     import configparser as ConfigParser
@@ -134,6 +133,17 @@ class Error(Exception):
         return d
 
 
+def override_required(method):
+    def abstract_method(self, *args, **kwargs):
+        method(self, *args, **kwargs)
+        raise NotImplementedError(
+            "Class %s needs to implement the %s() method" %
+            (type(self).__name__, method.__name__)
+        )
+    abstract_method.__doc__ = method.__doc__
+    return abstract_method
+
+
 def get_clean_root_logger(level=logging.INFO):
     """ Attempts to get logging module into clean slate state """
 
@@ -469,12 +479,13 @@ class JSONSchemaValidator(NoValidator):
         return res
 
 
-class MySQL(ObjectBase):
+class DataBase(ObjectBase):
 
     def __init__(
             self, req, log, host, user, password, dbname, port, retry_count,
             retry_pause, event_size_limit, catmap_filename, tagmap_filename):
         ObjectBase.__init__(self, req, log)
+
         self.host = host
         self.user = user
         self.password = password
@@ -497,20 +508,16 @@ class MySQL(ObjectBase):
 
         self.con = None
 
+    @override_required
     def connect(self):
-        self.con = my.connect(
-            host=self.host, user=self.user, passwd=self.password,
-            db=self.dbname, port=self.port, cursorclass=mycursors.DictCursor)
+        pass
 
+    @override_required
     def close(self):
-        try:
-            if self.con:
-                self.con.close()
-        except Exception:
-            pass
-        self.con = None
+        pass
 
-    __del__ = close
+    def __del__(self):
+        self.close()
 
     def repeat(self):
         """ Allows for graceful repeating of transactions self.retry_count
@@ -521,8 +528,7 @@ class MySQL(ObjectBase):
 
             for attempt in self.repeat():
                 with attempt as db:
-                    crs = db.query(...)
-                    # do something with crs
+                    res = db.query_all(...)
 
             Note that it's not reentrant (as is not underlying MySQL
             connection), so avoid nesting on the same MySQL object.
@@ -540,8 +546,7 @@ class MySQL(ObjectBase):
             exception. Can be used with self.repeat(), or alone as:
 
             with self as db:
-                crs = db.query(...)
-                # do something with crs
+                res = db.query_all(...)
 
             Note that it's not reentrant (as is not underlying MySQL
             connection), so avoid nesting on the same MySQL object.
@@ -550,6 +555,7 @@ class MySQL(ObjectBase):
             self.retry_attempt = 0
         return self
 
+    @override_required
     def __exit__(self, exc_type, exc_val, exc_tb):
         """ Context manager protocol. If db exception is fired and
             self.retry_attempt is not zero, it is only logged and
@@ -557,110 +563,87 @@ class MySQL(ObjectBase):
             open transaction is rolled back.
             In case of no exception, transaction gets commited.
         """
-        if not exc_type:
-            self.con.commit()
-            self.retry_attempt = 0
-        else:
-            try:
-                if self.con:
-                    self.con.rollback()
-            except my.Error:
-                pass
-            try:
-                self.close()
-            except my.Error:
-                pass
-            if self.retry_attempt:
-                self.log.info("Database error (%d attempts left): %s %s" % (self.retry_attempt, exc_type.__name__, exc_val))
-                return True
 
-    def query(self, *args, **kwargs):
-        if not self.con:
-            self.connect()
-        crs = self.con.cursor()
-        self.log.debug("execute: %s %s" % (args, kwargs))
-        crs.execute(*args, **kwargs)
-        return crs
+    @override_required
+    def execute(self, query, params, ret=None):
+        """Execute the provided queries; discard the result"""
 
-    def _get_comma_perc(self, l):
-        return ','.join(['%s'] * len(l))
+    @override_required
+    def query_all(self, query, params, ret=-1):
+        """Execute the provided queries; return list of all rows as dicts of the ret-th query (0 based)"""
 
-    def _get_not(self, b):
-        return "" if b else "NOT"
+    @override_required
+    def query_one(self, query, prams, ret=-1):
+        """Execute the provided queries; return the first result of the ret-th query (0 based)"""
+
+    @override_required
+    def query_rowcount(self, query, params, ret=-1):
+        """Execute provided query; return the number of affected rows or the number of returned rows of the ret-th query (0 based)"""
+
+    @override_required
+    def _build_get_client_by_name(self, cert_names, name, secret):
+        """Build query and params for client lookup"""
 
     def get_client_by_name(self, cert_names=None, name=None, secret=None):
-        query = ["SELECT * FROM clients WHERE valid = 1"]
-        params = []
-        if name:
-            query.append(" AND name = %s")
-            params.append(name.lower())
-        if secret:
-            query.append(" AND secret = %s")
-            params.append(secret)
-        if cert_names:
-            query.append(" AND hostname IN (%s)" % self._get_comma_perc(cert_names))
-            params.extend(n.lower() for n in cert_names)
+        query, params, ret = self._build_get_client_by_name(cert_names, name, secret)
 
         for attempt in self.repeat():
             with attempt as db:
-                rows = db.query("".join(query), params).fetchall()
+                rows = db.query_all(query, params, ret)
                 if len(rows) > 1:
                     self.log.warning(
-                        "get_client_by_name: query returned more than one result (cert_names = %s, name = %s, secret = %s): %s" % (
-                            cert_names, name, secret, ", ".join([str(Client(**row)) for row in rows])))
+                        "get_client_by_name: query returned more than one result (cert_names = %s, name = %s, secret = %s): %s" %
+                        (cert_names, name, secret, ", ".join([str(Client(**row)) for row in rows]))
+                    )
                     return None
 
                 return Client(**rows[0]) if rows else None
 
+    @override_required
+    def _build_get_clients(self, id):
+        """Build query and params for client lookup by id"""
+
     def get_clients(self, id=None):
-        query = ["SELECT * FROM clients"]
-        params = []
-        if id:
-            query.append("WHERE id = %s")
-            params.append(id)
-        query.append("ORDER BY id")
+        query, params, ret = self._build_get_clients(id)
+
         for attempt in self.repeat():
             with attempt as db:
-                rows = db.query(" ".join(query), params).fetchall()
+                rows = db.query_all(query, params, ret=ret)
                 return [Client(**row) for row in rows]
 
+    @override_required
+    def _build_add_modify_client(self, id, **kwargs):
+        """Build query and params for adding/modifying client"""
+
     def add_modify_client(self, id=None, **kwargs):
-        query = []
-        params = []
-        uquery = []
-        if id is None:
-            query.append("INSERT INTO clients SET")
-            uquery.append("registered = now()")
-        else:
-            query.append("UPDATE clients SET")
-        for attr in set(Client._fields) - set(["id", "registered"]):
-            val = kwargs.get(attr, None)
-            if val is not None:
-                if attr == "secret" and val == "":  # disable secret
-                    val = None
-                uquery.append("`%s` = %%s" % attr)
-                params.append(val)
-        if not uquery:
+        if id is not None and all(kwargs.get(attr, None) is None for attr in set(Client._fields) - {"id", "registered"}):
             return id
-        query.append(", ".join(uquery))
-        if id is not None:
-            query.append("WHERE id = %s")
-            params.append(id)
+
+        query, params, ret = self._build_add_modify_client(id, **kwargs)
+
         for attempt in self.repeat():
             with attempt as db:
-                crs = db.query(" ".join(query), params)
-                newid = crs.lastrowid if id is None else id
+                res_id = db.query_one(query, params, ret=ret)["id"]
+                newid = res_id if id is None else id
                 return newid
 
+    @override_required
+    def _build_get_debug_version(self):
+        pass
+
+    @override_required
+    def _build_get_debug_tablestat(self):
+        pass
+
     def get_debug(self):
+        vquery, vparams, vret = self._build_get_debug_version()
+        tquery, tparams, tret = self._build_get_debug_tablestat()
         for attempt in self.repeat():
             with attempt as db:
-                rows = db.query("SELECT VERSION() AS VER").fetchall()
-                tablestat = db.query("SHOW TABLE STATUS").fetchall()
                 return {
-                    "db": "MySQL",
-                    "version": rows[0]["VER"],
-                    "tables": tablestat
+                    "db": type(self).__name__,
+                    "version": db.query_one(vquery, vparams, vret)["version"],
+                    "tables": db.query_all(tquery, tparams, tret)
                 }
 
     def getMaps(self, section, variables):
@@ -671,10 +654,21 @@ class MySQL(ObjectBase):
             except KeyError:
                 raise self.req.error(
                     message="Wrong tag or category used in query.",
-                    error=422, exc=sys.exc_info(), key=v)
+                    error=422, exc=sys.exc_info(), key=v
+                )
             maps.append(mapped)
         return set(maps)    # unique
 
+    @override_required
+    def _build_fetch_events(
+            self, client, id, count,
+            cat, nocat, tag, notag, group, nogroup):
+        """Build query and params for fetching events based on id, count and category, tag and group filters"""
+
+    @override_required
+    def _load_event_json(self, data):
+        """Return decoded json from data loaded from database, if unable to decode, return None"""
+
     def fetch_events(
             self, client, id, count,
             cat=None, nocat=None,
@@ -694,43 +688,16 @@ class MySQL(ObjectBase):
                 message="Unrealizable conditions. Choose group or nogroup option.",
                 error=422, group=group, nogroup=nogroup)
 
-        query = ["SELECT e.id, e.data FROM clients c RIGHT JOIN events e ON c.id = e.client_id WHERE e.id > %s"]
-        params = [id or 0]
-
-        if cat or nocat:
-            cats = self.getMaps(self.catmap, (cat or nocat))
-            query.append(
-                " AND e.id %s IN (SELECT event_id FROM event_category_mapping WHERE category_id IN (%s))" % (
-                    self._get_not(cat), self._get_comma_perc(cats)))
-            params.extend(cats)
-
-        if tag or notag:
-            tags = self.getMaps(self.tagmap, (tag or notag))
-            query.append(
-                " AND e.id %s IN (SELECT event_id FROM event_tag_mapping WHERE tag_id IN (%s))" % (
-                    self._get_not(tag), self._get_comma_perc(tags)))
-            params.extend(tags)
-
-        if group or nogroup:
-            subquery = []
-            for name in (group or nogroup):
-                escaped_name = name.replace('&', '&&').replace("_", "&_").replace("%", "&%")  # escape for LIKE
-                subquery.append("c.name = %s")                                # exact client
-                params.append(name)
-                subquery.append("c.name LIKE CONCAT(%s, '.%%') ESCAPE '&'")   # whole subtree
-                params.append(escaped_name)
-
-            query.append(" AND %s (%s)" % (self._get_not(group), " OR ".join(subquery)))
-
-        query.append(" AND e.valid = 1 LIMIT %s")
-        params.append(count)
-
-        query_string = "".join(query)
-
+        query, params, ret = self._build_fetch_events(
+            client, id, count,
+            cat, nocat,
+            tag, notag,
+            group, nogroup
+        )
         row = None
         for attempt in self.repeat():
             with attempt as db:
-                row = db.query(query_string, params).fetchall()
+                row = db.query_all(query, params, ret=ret)
 
         if row:
             maxid = max(r['id'] for r in row)
@@ -739,9 +706,8 @@ class MySQL(ObjectBase):
 
         events = []
         for r in row:
-            try:
-                e = json.loads(r["data"])
-            except Exception:
+            e = self._load_event_json(r["data"])
+            if e is None:  # null cannot be valid event JSON
                 # Note that we use Error object just for proper formatting,
                 # but do not raise it; from client perspective invalid
                 # events get skipped silently.
@@ -749,111 +715,767 @@ class MySQL(ObjectBase):
                     message="Unable to deserialize JSON event from db, id=%s" % r["id"],
                     error=500, exc=sys.exc_info(), id=r["id"])
                 err.log(self.log, prio=logging.WARNING)
-            events.append(e)
-
+            else:
+                events.append(e)
         return {
             "lastid": maxid,
             "events": events
         }
 
+    @override_required
+    def _build_store_events_event(self, client, event, raw_event):
+        """Build query and params for event insertion"""
+
+    @override_required
+    def _build_store_events_categories(self, event_id, cat_ids):
+        """Build query and params for insertion of event-categories mapping"""
+
+    @override_required
+    def _build_store_events_tags(self, event_id, tag_ids):
+        """Build query and params for insertion of event-tags mapping"""
+
     def store_events(self, client, events, events_raw):
         try:
             for attempt in self.repeat():
                 with attempt as db:
                     for event, raw_event in zip(events, events_raw):
-                        lastid = db.query(
-                            "INSERT INTO events (received,client_id,data) VALUES (NOW(), %s, %s)",
-                            (client.id, raw_event)).lastrowid
+                        equery, eparams, eret = self._build_store_events_event(client, event, raw_event)
+                        lastid = db.query_one(equery, eparams, ret=eret)["id"]
 
                         catlist = event.get('Category', ["Other"])
-                        cats = set(catlist) | set(cat.split(".", 1)[0] for cat in catlist)
-                        for cat in cats:
-                            cat_id = self.catmap.get(cat, self.catmap_other)
-                            db.query("INSERT INTO event_category_mapping (event_id,category_id) VALUES (%s, %s)", (lastid, cat_id))
+                        cats = set(catlist) | {cat.split(".", 1)[0] for cat in catlist}
+                        cat_ids = [self.catmap.get(cat, self.catmap_other) for cat in cats]
+                        cquery, cparams, _ = self._build_store_events_categories(lastid, cat_ids)
+                        db.execute(cquery, cparams)
 
                         nodes = event.get('Node', [])
-                        tags = []
-                        for node in nodes:
-                            tags.extend(node.get('Type', []))
-                        for tag in set(tags):
-                            tag_id = self.tagmap.get(tag, self.tagmap_other)
-                            db.query("INSERT INTO event_tag_mapping (event_id,tag_id) VALUES (%s, %s)", (lastid, tag_id))
+                        tags = {tag for node in nodes for tag in node.get('Type', [])}
+                        if tags:
+                            tag_ids = [self.tagmap.get(tag, self.tagmap_other) for tag in tags]
+                            tquery, tparams, _ = self._build_store_events_tags(lastid, tag_ids)
+                            db.execute(tquery, tparams)
+
                     return []
         except Exception as e:
             exception = self.req.error(message="DB error", error=500, exc=sys.exc_info(), env=self.req.env)
             exception.log(self.log)
             return [{"error": 500, "message": "DB error %s" % type(e).__name__}]
 
+    @override_required
+    def _build_insert_last_received_id(self, client, id):
+        """Build query and params for insertion of the last event id received by client"""
+
     def insertLastReceivedId(self, client, id):
         self.log.debug("insertLastReceivedId: id %i for client %i(%s)" % (id, client.id, client.hostname))
+        query, params, _ = self._build_insert_last_received_id(client, id)
         for attempt in self.repeat():
             with attempt as db:
-                db.query("INSERT INTO last_events(client_id, event_id, timestamp) VALUES(%s, %s, NOW())", (client.id, id))
+                db.execute(query, params)
+
+    @override_required
+    def _build_get_last_event_id(self):
+        """Build query and params for querying the id of the last inserted event"""
 
     def getLastEventId(self):
+        query, params, ret = self._build_get_last_event_id()
         for attempt in self.repeat():
             with attempt as db:
-                row = db.query("SELECT MAX(id) as id FROM events").fetchall()[0]
-                return row['id'] or 1
+                id_ = db.query_one(query, params, ret=ret)["id"]
+                return id_ or 1
+
+    @override_required
+    def _build_get_last_received_id(self, client):
+        """Build query and params for querying the last event id received by client"""
 
     def getLastReceivedId(self, client):
+        query, params, ret = self._build_get_last_received_id(client)
         for attempt in self.repeat():
             with attempt as db:
-                res = db.query(
-                    "SELECT event_id as id FROM last_events WHERE client_id = %s ORDER BY last_events.id DESC LIMIT 1",
-                    (client.id,)).fetchall()
-                try:
-                    row = res[0]
-                except IndexError:
+                res = db.query_one(query, params, ret=ret)
+
+                if res is None:
                     id = None
-                    self.log.debug("getLastReceivedId: probably first access, unable to get id for client %i(%s)" % (
-                        client.id, client.hostname))
+                    self.log.debug("getLastReceivedId: probably first access, unable to get id for client %i(%s)" %
+                        (client.id, client.hostname))
                 else:
-                    id = row["id"]
-                    self.log.debug("getLastReceivedId: id %i for client %i(%s)" % (id, client.id, client.hostname))
+                    id = res["id"] or 1
+                    self.log.debug("getLastReceivedId: id %i for client %i(%s)" %
+                        (id, client.id, client.hostname))
 
                 return id
 
+    @override_required
+    def _build_load_maps_tags(self):
+        """Build query and params for updating the tag map"""
+
+    @override_required
+    def _build_load_maps_cats(self):
+        """Build query and params for updating the catetgory map"""
+
     def load_maps(self):
+        tquery, tparams, _ = self._build_load_maps_tags()
+        cquery, cparams, _ = self._build_load_maps_cats()
         with self as db:
-            db.query("DELETE FROM tags")
-            for tag, num in self.tagmap.items():
-                db.query("INSERT INTO tags(id, tag) VALUES (%s, %s)", (num, tag))
-            db.query("DELETE FROM categories")
-            for cat_subcat, num in self.catmap.items():
-                catsplit = cat_subcat.split(".", 1)
-                category = catsplit[0]
-                subcategory = catsplit[1] if len(catsplit) > 1 else None
-                db.query(
-                    "INSERT INTO categories(id, category, subcategory, cat_subcat) VALUES (%s, %s, %s, %s)",
-                    (num, category, subcategory, cat_subcat))
+            db.execute(tquery, tparams)
+            db.execute(cquery, cparams)
+
+    @override_required
+    def _build_purge_lastlog(self, days):
+        """Build query and params for purging stored client last event mapping older than days"""
 
     def purge_lastlog(self, days):
+        query, params, ret = self._build_purge_lastlog(days)
+        with self as db:
+            return db.query_rowcount(query, params, ret=ret)
+
+    @override_required
+    def _build_purge_events_get_id(self, days):
+        """Build query and params to get largest event id of events older than days"""
+
+    @override_required
+    def _build_purge_events_events(self, id_):
+        """Build query and params to remove events older then days and their mappings"""
+
+    def purge_events(self, days):
+        iquery, iparams, iret = self._build_purge_events_get_id(days)
         with self as db:
-            return db.query(
+            id_ = db.query_one(iquery, iparams, ret=iret)["id"]
+            if id_ is None:
+                return 0
+            equery, eparams, eret = self._build_purge_events_events(id_)
+            affected = db.query_rowcount(equery, eparams, ret=eret)
+            return affected
+
+
+class DataBaseAPIv2(DataBase):
+
+    def __init__(self, req, log, host, user, password, dbname, port, retry_count,
+            retry_pause, event_size_limit, catmap_filename, tagmap_filename):
+
+        super().__init__(req, log, host, user, password, dbname, port, retry_count,
+            retry_pause, event_size_limit, catmap_filename, tagmap_filename)
+
+        self.db = None
+        self.con = None
+
+    def close(self):
+        try:
+            if self.con:
+                self.con.close()
+        except Exception:
+            pass
+        self.con = None
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        """ Context manager protocol. If db exception is fired and
+            self.retry_attempt is not zero, it is only logged and
+            does not propagate, otherwise it propagates up. Also
+            open transaction is rolled back.
+            In case of no exception, transaction gets commited.
+        """
+        if exc_type is None:
+            self.con.commit()
+            self.retry_attempt = 0
+        else:
+            try:
+                if self.con is not None:
+                    self.con.rollback()
+            except self.db.Error:
+                pass
+            try:
+                self.close()
+            except self.db.Error:
+                pass
+            if self.retry_attempt > 0:
+                self.log.info("Database error (%d attempts left): %s %s" %
+                              (self.retry_attempt, exc_type.__name__, exc_val))
+                return True
+
+    def _query(self, *args, **kwargs):
+        if not self.con:
+            self.connect()
+        crs = self.con.cursor()
+        self.log.debug("execute: %s %s" % (args, kwargs))
+        crs.execute(*args, **kwargs)
+        return crs
+
+    def _query_multiple(self, query, params, ret, fetch):
+        res = None
+        for n, (q, p) in enumerate(zip(query, params)):
+            cur = self._query(q, p)
+            if n == ret:
+                res = fetch(cur)
+        if ret == -1:  # fetch the result of the last query
+            res = fetch(cur)
+        return res
+
+    def execute(self, query, params, ret=None):
+        """Execute the provided queries; discard the result"""
+        self._query_multiple(query, params, None, None)
+
+    def query_all(self, query, params, ret=-1):
+        """Execute the provided queries; return list of all rows as dicts of the ret-th query (0 based)"""
+        return self._query_multiple(query, params, ret, lambda cur: cur.fetchall())
+
+    def query_one(self, query, params, ret=-1):
+        """Execute the provided queries; return the first result of the ret-th query (0 based)"""
+        return self._query_multiple(query, params, ret, lambda cur: cur.fetchone())
+
+    def query_rowcount(self, query, params, ret=-1):
+        """Execute provided query; return the number of affected rows or the number of returned rows of the ret-th query (0 based)"""
+        return self._query_multiple(query, params, ret, lambda cur: cur.rowcount)
+
+    def _get_comma_perc(self, l):
+        return ",".join(repeat("%s", l if isinstance(l, int) else len(l)))
+
+    def _get_comma_perc_n(self, n, l):
+        return ", ".join(repeat("(%s)" % self._get_comma_perc(n), len(l)))
+
+    def _get_not(self, b):
+        return "" if b else "NOT"
+
+
+class MySQL(DataBaseAPIv2):
+
+    def __init__(
+            self, req, log, host, user, password, dbname, port, retry_count,
+            retry_pause, event_size_limit, catmap_filename, tagmap_filename):
+
+        super().__init__(req, log, host, user, password, dbname, port, retry_count,
+            retry_pause, event_size_limit, catmap_filename, tagmap_filename)
+
+        import MySQLdb as db
+        import MySQLdb.cursors as mycursors
+        self.db = db
+        self.mycursors = mycursors
+
+    def connect(self):
+        self.con = self.db.connect(
+            host=self.host, user=self.user, passwd=self.password,
+            db=self.dbname, port=self.port, cursorclass=self.mycursors.DictCursor)
+
+    def _build_get_client_by_name(self, cert_names=None, name=None, secret=None):
+        """Build query and params for client lookup"""
+        query = ["SELECT * FROM clients WHERE valid = 1"]
+        params = []
+        if name:
+            query.append(" AND name = %s")
+            params.append(name.lower())
+        if secret:
+            query.append(" AND secret = %s")
+            params.append(secret)
+        if cert_names:
+            query.append(" AND hostname IN (%s)" % self._get_comma_perc(cert_names))
+            params.extend(n.lower() for n in cert_names)
+
+        return ["".join(query)], [params], 0
+
+    def _build_get_clients(self, id):
+        """Build query and params for client lookup by id"""
+        query = ["SELECT * FROM clients"]
+        params = []
+        if id:
+            query.append("WHERE id = %s")
+            params.append(id)
+        query.append("ORDER BY id")
+
+        return [" ".join(query)], [params], 0
+
+    def _build_add_modify_client(self, id, **kwargs):
+        """Build query and params for adding/modifying client"""
+        query = []
+        params = []
+        uquery = []
+        if id is None:
+            query.append("INSERT INTO clients SET")
+            uquery.append("registered = now()")
+        else:
+            query.append("UPDATE clients SET")
+        for attr in set(Client._fields) - set(["id", "registered"]):
+            val = kwargs.get(attr, None)
+            if val is not None:  # guaranteed at least one is not None
+                if attr == "secret" and val == "":  # disable secret
+                    val = None
+                uquery.append("`%s` = %%s" % attr)
+                params.append(val)
+
+        query.append(", ".join(uquery))
+        if id is not None:
+            query.append("WHERE id = %s")
+            params.append(id)
+        return (
+            [" ".join(query), 'SELECT LAST_INSERT_ID() AS id'],
+            [params, []],
+            1
+        )
+
+    def _build_get_debug_version(self):
+        return ["SELECT VERSION() AS version"], [()], 0
+
+    def _build_get_debug_tablestat(self):
+        return ["SHOW TABLE STATUS"], [()], 0
+
+    def _load_event_json(self, data):
+        """Return decoded json from data loaded from database, if unable to decode, return None"""
+        try:
+            return json.loads(data)
+        except Exception:
+            return None
+
+    def _build_fetch_events(
+            self, client, id, count,
+            cat, nocat, tag, notag, group, nogroup):
+        query = ["SELECT e.id, e.data FROM clients c RIGHT JOIN events e ON c.id = e.client_id WHERE e.id > %s"]
+        params = [id or 0]
+
+        if cat or nocat:
+            cats = self.getMaps(self.catmap, (cat or nocat))
+            query.append(
+                " AND e.id %s IN (SELECT event_id FROM event_category_mapping WHERE category_id IN (%s))" %
+                (self._get_not(cat), self._get_comma_perc(cats))
+            )
+            params.extend(cats)
+
+        if tag or notag:
+            tags = self.getMaps(self.tagmap, (tag or notag))
+            query.append(
+                " AND e.id %s IN (SELECT event_id FROM event_tag_mapping WHERE tag_id IN (%s))" %
+                (self._get_not(tag), self._get_comma_perc(tags))
+            )
+            params.extend(tags)
+
+        if group or nogroup:
+            subquery = []
+            for name in (group or nogroup):
+                escaped_name = name.replace('&', '&&').replace("_", "&_").replace("%", "&%")  # escape for LIKE
+                subquery.append("c.name = %s")                 # exact client
+                params.append(name)
+                subquery.append("c.name LIKE CONCAT(%s, '.%%') ESCAPE '&'")   # whole subtree
+                params.append(escaped_name)
+
+            query.append(" AND %s (%s)" %
+                (self._get_not(group), " OR ".join(subquery)))
+
+        query.append(" AND e.valid = 1 LIMIT %s")
+        params.append(count)
+
+        return ["".join(query)], [params], 0
+
+    def _build_store_events_event(self, client, event, raw_event):
+        """Build query and params for event insertion"""
+        return (
+            [
+                "INSERT INTO events (received,client_id,data) VALUES (NOW(), %s, %s)",
+                "SELECT LAST_INSERT_ID() AS id"
+            ],
+            [(client.id, raw_event), ()],
+            1
+        )
+
+    def _build_store_events_categories(self, event_id, cat_ids):
+        """Build query and params for insertion of event-categories mapping"""
+        return (
+            ["INSERT INTO event_category_mapping (event_id,category_id) VALUES " +
+                self._get_comma_perc_n(2, cat_ids)],
+            [tuple(param for cat_id in cat_ids for param in (event_id, cat_id))],
+            None
+        )
+
+    def _build_store_events_tags(self, event_id, tag_ids):
+        """Build query and params for insertion of event-tags mapping"""
+        return (
+            ["INSERT INTO event_tag_mapping (event_id,tag_id) VALUES " +
+                self._get_comma_perc_n(2, tag_ids)],
+            [tuple(param for tag_id in tag_ids for param in (event_id, tag_id))],
+            None
+        )
+
+    def _build_insert_last_received_id(self, client, id):
+        """Build query and params for insertion of the last event id received by client"""
+        return (
+            ["INSERT INTO last_events(client_id, event_id, timestamp) VALUES(%s, %s, NOW())"],
+            [(client.id, id)],
+            None
+        )
+
+    def _build_get_last_event_id(self):
+        """Build query and params for querying the id of the last inserted event"""
+        return ["SELECT MAX(id) as id FROM events"], [()], 0
+
+    def _build_get_last_received_id(self, client):
+        """Build query and params for querying the last event id received by client"""
+        return (
+            ["SELECT event_id as id FROM last_events WHERE client_id = %s ORDER BY last_events.id DESC LIMIT 1"],
+            [(client.id,)],
+            0
+        )
+
+    def _build_load_maps_tags(self):
+        """Build query and params for updating the tag map"""
+        return (
+            [
+                "DELETE FROM tags",
+                "INSERT INTO tags(id, tag) VALUES " +
+                    self._get_comma_perc_n(2, self.tagmap)
+            ],
+            [
+                (),
+                tuple(param for tag, num in self.tagmap.items() for param in (num, tag))
+            ],
+            None
+        )
+
+    def _build_load_maps_cats(self):
+        """Build query and params for updating the catetgory map"""
+        params = []
+        for cat_subcat, num in self.catmap.items():
+            catsplit = cat_subcat.split(".", 1)
+            category = catsplit[0]
+            subcategory = catsplit[1] if len(catsplit) > 1 else None
+            params.extend((num, category, subcategory, cat_subcat))
+
+        return (
+            [
+                "DELETE FROM categories",
+                "INSERT INTO categories(id, category, subcategory, cat_subcat) VALUES " +
+                    self._get_comma_perc_n(4, self.catmap)
+            ],
+            [
+                (),
+                tuple(params)
+            ],
+            None
+        )
+
+    def _build_purge_lastlog(self, days):
+        """Build query and params for purging stored client last event mapping older than days"""
+        return (
+            [
                 "DELETE FROM last_events "
                 " USING last_events LEFT JOIN ("
                 "    SELECT MAX(id) AS last FROM last_events"
                 "    GROUP BY client_id"
                 " ) AS maxids ON last=id"
                 " WHERE timestamp < DATE_SUB(CURDATE(), INTERVAL %s DAY) AND last IS NULL",
-                (days,)).rowcount
+            ],
+            [(days,)],
+            0
+        )
+
+    def _build_purge_events_get_id(self, days):
+        """Build query and params to get largest event id of events older than days"""
+        return (
+            [
+                "SELECT MAX(id) as id"
+                "  FROM events"
+                "  WHERE received < DATE_SUB(CURDATE(), INTERVAL %s DAY)"
+            ],
+            [(days,)],
+            0
+        )
+
+    def _build_purge_events_events(self, id_):
+        """Build query and params to remove events older then days and their mappings"""
+        return (
+            [
+                "DELETE FROM event_category_mapping WHERE event_id <= %s",
+                "DELETE FROM event_tag_mapping WHERE event_id <= %s",
+                "DELETE FROM events WHERE id <= %s",
+            ],
+            [(id_,), (id_,), (id_,)],
+            2
+        )
+
+
+class PostgreSQL(DataBaseAPIv2):
 
-    def purge_events(self, days):
-        with self as db:
-            affected = 0
-            id_ = db.query(
+    def __init__(
+            self, req, log, host, user, password, dbname, port, retry_count,
+            retry_pause, event_size_limit, catmap_filename, tagmap_filename):
+
+        super().__init__(req, log, host, user, password, dbname, port, retry_count,
+            retry_pause, event_size_limit, catmap_filename, tagmap_filename)
+
+        import psycopg2 as db
+        from psycopg2 import sql as ppgsql
+        import psycopg2.extras as ppgextra
+        self.db = db
+        self.ppgsql = ppgsql
+        self.ppgextra = ppgextra
+
+    def connect(self):
+        self.con = self.db.connect(
+            host=self.host, user=self.user, password=self.password,
+            dbname=self.dbname, port=self.port, cursor_factory=self.ppgextra.RealDictCursor)
+
+    def _build_get_client_by_name(self, cert_names=None, name=None, secret=None):
+        """Build query and params for client lookup"""
+        query = ["SELECT * FROM clients WHERE valid = 1"]
+        params = []
+        if name:
+            query.append(" AND name = %s")
+            params.append(name.lower())
+        if secret:
+            query.append(" AND secret = %s")
+            params.append(secret)
+        if cert_names:
+            query.append(" AND hostname IN (%s)" % self._get_comma_perc(cert_names))
+            params.extend(n.lower() for n in cert_names)
+
+        return ["".join(query)], [params], 0
+
+    def _build_get_clients(self, id):
+        """Build query and params for client lookup by id"""
+        query = ["SELECT * FROM clients"]
+        params = []
+        if id:
+            query.append("WHERE id = %s")
+            params.append(id)
+        query.append("ORDER BY id")
+
+        return [" ".join(query)], [params], 0
+
+    def _build_add_modify_client(self, id, **kwargs):
+        """Build query and params for adding/modifying client"""
+        fields = set(Client._fields) - {"id", "registered"}
+        cols, params = map(
+            list,
+            zip(
+                *(
+                    (k, None)  # disable secret
+                    if k == "secret" and v == "" else
+                    (k, v)
+                    for k, v in kwargs.items()
+                    if v is not None and k in fields
+                )
+            )
+        )
+
+        if id is None:
+            query = self.ppgsql.SQL('INSERT INTO clients ("registered", {}) VALUES (NOW(), {}) RETURNING id').format(
+                self.ppgsql.SQL(", ").join(map(self.ppgsql.Identifier, cols)),
+                self.ppgsql.SQL(", ").join(self.ppgsql.Placeholder() * len(cols))
+            )
+        elif not cols:
+            return ["SELECT %s AS id"], [(id,)], 0
+        else:
+            query = self.ppgsql.SQL("UPDATE clients SET {} WHERE id = {} RETURNING id").format(
+                self.ppgsql.SQL(", ").join(
+                    self.ppgsql.SQL("{} = {}").format(
+                        self.ppgsql.Identifier(col),
+                        self.ppgsql.Placeholder()
+                    ) for col in cols
+                ),
+                self.ppgsql.Placeholder()
+            )
+            params.append(id)
+
+        return [query], [params], 0
+
+    def _build_get_debug_version(self):
+        return ["SELECT setting AS version FROM pg_settings WHERE name = 'server_version'"], [()], 0
+
+    def _build_get_debug_tablestat(self):
+        return [
+            "SELECT "
+                'tablename AS "Name", '
+                'relnatts AS "Columns", '
+                'n_live_tup AS "Rows", '
+                'pg_catalog.pg_size_pretty(pg_catalog.pg_table_size(oid)) AS "Table_size", '
+                'pg_catalog.pg_size_pretty(pg_catalog.pg_indexes_size(oid)) AS "Index_size", '
+                'coll.collations AS "Collations" '
+            "FROM "
+                "pg_catalog.pg_tables tbls "
+                "LEFT OUTER JOIN pg_catalog.pg_class cls "
+                "ON tbls.tablename=cls.relname "
+                "LEFT OUTER JOIN pg_catalog.pg_stat_user_tables sut "
+                "ON tbls.tablename=sut.relname "
+                "LEFT OUTER JOIN ("
+                    "SELECT "
+                        "table_name, "
+                        "string_agg("
+                            "DISTINCT COALESCE("
+                                "collation_name, "
+                                "("
+                                    "SELECT "
+                                        "datcollate "
+                                    "FROM "
+                                        "pg_catalog.pg_database "
+                                    "WHERE "
+                                        "datname=%s"
+                                ")"
+                            "), "
+                            "','"
+                        ") AS collations "
+                    "FROM "
+                        "information_schema.columns "
+                    "GROUP BY "
+                        "table_name"
+                ") coll "
+                "ON tbls.tablename=coll.table_name "
+            "WHERE "
+                "tbls.schemaname='public' "
+                "AND tbls.tableowner=%s"
+        ], [(self.dbname, self.user)], 0
+
+    def _load_event_json(self, data):
+        """Return decoded json from data loaded from database, if unable to decode, return None"""
+        try:
+            return json.loads(data.tobytes())
+        except Exception:
+            return None
+
+    def _build_fetch_events(
+            self, client, id, count,
+            cat, nocat, tag, notag, group, nogroup):
+
+        query = ["SELECT e.id, e.data FROM clients c RIGHT JOIN events e ON c.id = e.client_id WHERE e.id > %s"]
+        params = [id or 0]
+
+        if cat or nocat:
+            cats = self.getMaps(self.catmap, (cat or nocat))
+            query.append(
+                " AND e.id %s IN (SELECT event_id FROM event_category_mapping WHERE category_id IN (%s))" %
+                (self._get_not(cat), self._get_comma_perc(cats))
+            )
+            params.extend(cats)
+
+        if tag or notag:
+            tags = self.getMaps(self.tagmap, (tag or notag))
+            query.append(
+                " AND e.id %s IN (SELECT event_id FROM event_tag_mapping WHERE tag_id IN (%s))" %
+                (self._get_not(tag), self._get_comma_perc(tags))
+            )
+            params.extend(tags)
+
+        if group or nogroup:
+            subquery = []
+            for name in group or nogroup:
+                name = name.lower()  # assumes only lowercase names
+                escaped_name = name.replace('&', '&&').replace("_", "&_").replace("%", "&%")  # escape for LIKE
+                subquery.append("c.name = %s")                          # exact client
+                params.append(name)
+                subquery.append("c.name LIKE %s || '.%%' ESCAPE '&'")   # whole subtree
+                params.append(escaped_name)
+
+            query.append(" AND %s (%s)" % (self._get_not(group), " OR ".join(subquery)))
+
+        query.append(" AND e.valid = 1 LIMIT %s")
+        params.append(count)
+
+        return ["".join(query)], [params], 0
+
+    def _build_store_events_event(self, client, event, raw_event):
+        """Build query and params for event insertion"""
+        return (
+            ["INSERT INTO events (received,client_id,data) VALUES (NOW(), %s, %s) RETURNING id"],
+            [(client.id, raw_event)],
+            0
+        )
+
+    def _build_store_events_categories(self, event_id, cat_ids):
+        """Build query and params for insertion of event-categories mapping"""
+        return (
+            ["INSERT INTO event_category_mapping (event_id,category_id) VALUES " +
+                self._get_comma_perc_n(2, cat_ids)],
+            [tuple(param for cat_id in cat_ids for param in (event_id, cat_id))],
+            None
+        )
+
+    def _build_store_events_tags(self, event_id, tag_ids):
+        """Build query and params for insertion of event-tags mapping"""
+        return (
+            ["INSERT INTO event_tag_mapping (event_id,tag_id) VALUES " +
+                self._get_comma_perc_n(2, tag_ids)],
+            [tuple(param for tag_id in tag_ids for param in (event_id, tag_id))],
+            None
+        )
+
+    def _build_insert_last_received_id(self, client, id):
+        """Build query and params for insertion of the last event id received by client"""
+        return (
+            ["INSERT INTO last_events(client_id, event_id, timestamp) VALUES(%s, %s, NOW())"],
+            [(client.id, None if id == 1 else id)],
+            None
+        )
+
+    def _build_get_last_event_id(self):
+        """Build query and params for querying the id of the last inserted event"""
+        return ["SELECT MAX(id) as id FROM events"], [()], 0
+
+    def _build_get_last_received_id(self, client):
+        """Build query and params for querying the last event id received by client"""
+        return (
+            ["SELECT event_id as id FROM last_events WHERE client_id = %s ORDER BY last_events.id DESC LIMIT 1"],
+            [(client.id,)],
+            0
+        )
+
+    def _build_load_maps_tags(self):
+        """Build query and params for updating the tag map"""
+        return (
+            [
+                "ALTER TABLE event_tag_mapping DROP CONSTRAINT event_tag_mapping_tag_id_fk",
+                "DELETE FROM tags",
+                "INSERT INTO tags(id, tag) VALUES " +
+                    self._get_comma_perc_n(2, self.tagmap),
+                'ALTER TABLE event_tag_mapping ADD CONSTRAINT "event_tag_mapping_tag_id_fk" FOREIGN KEY ("tag_id") REFERENCES "tags" ("id")'
+            ],
+            [(), (), tuple(param for tag, num in self.tagmap.items() for param in (num, tag)), ()],
+            None
+        )
+
+    def _build_load_maps_cats(self):
+        """Build query and params for updating the catetgory map"""
+        params = []
+        for cat_subcat, num in self.catmap.items():
+            catsplit = cat_subcat.split(".", 1)
+            category = catsplit[0]
+            subcategory = catsplit[1] if len(catsplit) > 1 else None
+            params.extend((num, category, subcategory, cat_subcat))
+
+        return (
+            [
+                "ALTER TABLE event_category_mapping DROP CONSTRAINT event_category_mapping_category_id_fk",
+                "DELETE FROM categories",
+                "INSERT INTO categories(id, category, subcategory, cat_subcat) VALUES " +
+                    self._get_comma_perc_n(4, self.catmap),
+                'ALTER TABLE event_category_mapping ADD CONSTRAINT "event_category_mapping_category_id_fk" FOREIGN KEY ("category_id") REFERENCES "categories" ("id")'
+            ],
+            [(), (), tuple(params), ()],
+            None
+        )
+
+    def _build_purge_lastlog(self, days):
+        """Build query and params for purging stored client last event mapping older than days"""
+        return (
+            [
+                "DELETE FROM last_events "
+                " USING last_events le LEFT JOIN ("
+                "    SELECT MAX(id) AS last FROM last_events"
+                "    GROUP BY client_id"
+                " ) AS maxids ON maxids.last=le.id"
+                " WHERE le.timestamp < CURRENT_DATE - INTERVAL %s DAY AND maxids.last IS NULL"
+            ],
+            [(str(days),)],
+            0
+        )
+
+    def _build_purge_events_get_id(self, days):
+        """Build query and params to get largest event id of events older than days"""
+        return (
+            [
                 "SELECT MAX(id) as id"
                 "  FROM events"
-                "  WHERE received < DATE_SUB(CURDATE(), INTERVAL %s DAY)",
-                (days,)
-            ).fetchall()[0]["id"]
-            if id_ is None:
-                return 0
-            affected = db.query("DELETE FROM events WHERE id <= %s", (id_,)).rowcount
-            db.query("DELETE FROM event_category_mapping WHERE event_id <= %s", (id_,))
-            db.query("DELETE FROM event_tag_mapping WHERE event_id <= %s", (id_,))
-            return affected
+                "  WHERE received < CURRENT_DATE - INTERVAL %s DAY"
+            ],
+            [(str(days),)],
+            0
+        )
+
+    def _build_purge_events_events(self, id_):
+        """Build query and params to remove events older then days and their mappings"""
+        return ["DELETE FROM events WHERE id <= %s"], [(id_,)], 0
 
 
 def expose(read=1, write=0, debug=0):
@@ -1245,7 +1867,7 @@ section_order = ("log", "db", "auth", "validator", "handler", "server")
 # "type" keyword in section may be used to choose other
 section_def = {
     "log": [FileLogger, SysLogger],
-    "db": [MySQL],
+    "db": [MySQL, PostgreSQL],
     "auth": [X509NameAuthenticator, PlainAuthenticator, X509Authenticator, X509MixMatchAuthenticator],
     "validator": [JSONSchemaValidator, NoValidator],
     "handler": [WardenHandler],
@@ -1305,8 +1927,22 @@ param_def = {
         "retry_pause": {"type": "natural", "default": 3},
         "retry_count": {"type": "natural", "default": 3},
         "event_size_limit": {"type": "natural", "default": 5*1024*1024},
-        "catmap_filename": {"type": "filepath", "default": path.join(path.dirname(__file__), "catmap_mysql.json")},
-        "tagmap_filename": {"type": "filepath", "default": path.join(path.dirname(__file__), "tagmap_mysql.json")}
+        "catmap_filename": {"type": "filepath", "default": path.join(path.dirname(__file__), "catmap_db.json")},
+        "tagmap_filename": {"type": "filepath", "default": path.join(path.dirname(__file__), "tagmap_db.json")}
+    },
+    PostgreSQL: {
+        "req": {"type": "obj", "default": "req"},
+        "log": {"type": "obj", "default": "log"},
+        "host": {"type": "str", "default": "localhost"},
+        "user": {"type": "str", "default": "warden"},
+        "password": {"type": "str", "default": ""},
+        "dbname": {"type": "str", "default": "warden3"},
+        "port": {"type": "natural", "default": 5432},
+        "retry_pause": {"type": "natural", "default": 3},
+        "retry_count": {"type": "natural", "default": 3},
+        "event_size_limit": {"type": "natural", "default": 5*1024*1024},
+        "catmap_filename": {"type": "filepath", "default": path.join(path.dirname(__file__), "catmap_db.json")},
+        "tagmap_filename": {"type": "filepath", "default": path.join(path.dirname(__file__), "tagmap_db.json")}
     },
     WardenHandler: {
         "req": {"type": "obj", "default": "req"},
@@ -1663,9 +2299,7 @@ def get_args():
     subargp_loadmaps = subargp.add_parser(
         "loadmaps", add_help=False,
         description=(
-            "Load 'categories' and 'tags' table from 'catmap_mysql.json' and 'tagmap_mysql.json'."
-            " Note that this is NOT needed for server at all, load them into db at will,"
-            " should you need to run your own specific SQL queries on data directly."
+            "Load 'categories' and 'tags' table from 'catmap_db.json' and 'tagmap_db.json'."
             " Note also that previous content of both tables will be lost."),
         help="load catmap and tagmap into db")
     subargp_loadmaps.set_defaults(command=load_maps)