Optimize postgresql ingest pipeline (elastic#7269)

The postgresql ingest pipeline was not performing so well.
This PR use the following rules to improve the situation.

- Anchor the Regular expression at the begining of the string.
- Merge the multiple statements into a single RE
- Do not use back reference for user/host delimiter.

Fixes: elastic#7201

Master branch to ingest 18 documents 26ms, this PR 11 ms.
Not I did not use dissect, since there are variations in the tokens.

(cherry picked from commit 4a41587)

CHANGELOG.asciidoc

@@ -36,6 +36,7 @@ https://github.com/elastic/beats/compare/v6.3.0...6.3[Check the HEAD diff]
 *Filebeat*
 
 - Comply with PostgreSQL database name format {pull}7198[7198]
+- Optimize PostgreSQL ingest pipeline to use anchored regexp and merge multiple regexp into a single expression. {pull}7269[7269]
 
 *Heartbeat*
 

filebeat/module/postgresql/log/ingest/pipeline.json

@@ -6,16 +6,11 @@
         "field": "message",
         "ignore_missing": true,
         "patterns": [
-          "%{LOCALDATETIME:postgresql.log.timestamp} %{WORD:postgresql.log.timezone} \\[%{NUMBER:postgresql.log.thread_id}\\] %{USERNAME:postgresql.log.user}@%{POSTGRESQL_DB_NAME:postgresql.log.database} %{WORD:postgresql.log.level}:  duration: %{NUMBER:postgresql.log.duration} ms  statement: %{MULTILINEQUERY:postgresql.log.query}",
-          "%{LOCALDATETIME:postgresql.log.timestamp} %{WORD:postgresql.log.timezone} \\[%{NUMBER:postgresql.log.thread_id}\\] \\[%{USERNAME:postgresql.log.user}\\]@\\[%{POSTGRESQL_DB_NAME:postgresql.log.database}\\] %{WORD:postgresql.log.level}:  duration: %{NUMBER:postgresql.log.duration} ms  statement: %{MULTILINEQUERY:postgresql.log.query}",
-          "%{LOCALDATETIME:postgresql.log.timestamp} %{WORD:postgresql.log.timezone} \\[%{NUMBER:postgresql.log.thread_id}\\] %{USERNAME:postgresql.log.user}@%{POSTGRESQL_DB_NAME:postgresql.log.database} %{WORD:postgresql.log.level}:  ?%{GREEDYDATA:postgresql.log.message}",
-          "%{LOCALDATETIME:postgresql.log.timestamp} %{WORD:postgresql.log.timezone} \\[%{NUMBER:postgresql.log.thread_id}\\] \\[%{USERNAME:postgresql.log.user}\\]@\\[%{POSTGRESQL_DB_NAME:postgresql.log.database}\\] %{WORD:postgresql.log.level}:  ?%{GREEDYDATA:postgresql.log.message}",
-          "%{LOCALDATETIME:postgresql.log.timestamp} %{WORD:postgresql.log.timezone} \\[%{NUMBER:postgresql.log.thread_id}\\] %{WORD:postgresql.log.level}:  ?%{GREEDYDATA:postgresql.log.message}"
+            "^%{LOCALDATETIME:postgresql.log.timestamp} %{WORD:postgresql.log.timezone} \\[%{NUMBER:postgresql.log.thread_id}\\] ((\\[%{USERNAME:postgresql.log.user}\\]@\\[%{POSTGRESQL_DB_NAME:postgresql.log.database}\\]|%{USERNAME:postgresql.log.user}@%{POSTGRESQL_DB_NAME:postgresql.log.database}) )?%{WORD:postgresql.log.level}:  (duration: %{NUMBER:postgresql.log.duration} ms  statement: %{GREEDYDATA:postgresql.log.query}|%{GREEDYDATA:postgresql.log.message})"
         ],
         "pattern_definitions": {
           "LOCALDATETIME": "[-0-9]+ %{TIME}",
-          "GREEDYDATA": ".*",
-          "MULTILINEQUERY" : "(.|\n|\t)*?;$",
+          "GREEDYDATA": "(.|\n|\t)*",
           "POSTGRESQL_DB_NAME": "[a-zA-Z0-9_]+[a-zA-Z0-9_\\$]*"
         }
       }

filebeat/tests/system/test_modules.py

@@ -91,7 +91,7 @@ def _test_expected_events(self, module, test_file, res, objects):
                     break
 
             assert found, "The following expected object was not found:\n {}\nSearched in: \n{}".format(
-                ev["_source"][module], objects)
+                pretty_json(ev["_source"][module]), pretty_json(objects))
 
     def run_on_file(self, module, fileset, test_file, cfgfile):
         print("Testing {}/{} on {}".format(module, fileset, test_file))
@@ -108,7 +108,8 @@ def run_on_file(self, module, fileset, test_file, cfgfile):
             "-c", cfgfile,
             "-modules={}".format(module),
             "-M", "{module}.*.enabled=false".format(module=module),
-            "-M", "{module}.{fileset}.enabled=true".format(module=module, fileset=fileset),
+            "-M", "{module}.{fileset}.enabled=true".format(
+                module=module, fileset=fileset),
             "-M", "{module}.{fileset}.var.paths=[{test_file}]".format(
                 module=module, fileset=fileset, test_file=test_file),
             "-M", "*.*.input.close_eof=true",
@@ -138,7 +139,8 @@ def run_on_file(self, module, fileset, test_file, cfgfile):
             assert obj["fileset"]["module"] == module, "expected fileset.module={} but got {}".format(
                 module, obj["fileset"]["module"])
 
-            assert "error" not in obj, "not error expected but got: {}".format(obj)
+            assert "error" not in obj, "not error expected but got: {}".format(
+                obj)
 
             if (module == "auditd" and fileset == "log") \
                     or (module == "osquery" and fileset == "result"):
@@ -229,13 +231,16 @@ def _run_ml_test(self, setup_flag, modules_flag):
         # Clean any previous state
         for df in self.es.transport.perform_request("GET", "/_xpack/ml/datafeeds/")["datafeeds"]:
             if df["datafeed_id"] == 'filebeat-nginx-access-response_code':
-                self.es.transport.perform_request("DELETE", "/_xpack/ml/datafeeds/" + df["datafeed_id"])
+                self.es.transport.perform_request(
+                    "DELETE", "/_xpack/ml/datafeeds/" + df["datafeed_id"])
 
         for df in self.es.transport.perform_request("GET", "/_xpack/ml/anomaly_detectors/")["jobs"]:
             if df["job_id"] == 'datafeed-filebeat-nginx-access-response_code':
-                self.es.transport.perform_request("DELETE", "/_xpack/ml/anomaly_detectors/" + df["job_id"])
+                self.es.transport.perform_request(
+                    "DELETE", "/_xpack/ml/anomaly_detectors/" + df["job_id"])
 
-        shutil.rmtree(os.path.join(self.working_dir, "modules.d"), ignore_errors=True)
+        shutil.rmtree(os.path.join(self.working_dir,
+                                   "modules.d"), ignore_errors=True)
 
         # generate a minimal configuration
         cfgfile = os.path.join(self.working_dir, "filebeat.yml")
@@ -302,3 +307,7 @@ def _run_ml_test(self, setup_flag, modules_flag):
                                    max_timeout=30)
 
         beat.kill()
+
+
+def pretty_json(obj):
+    return json.dumps(obj, indent=2, separators=(',', ': '))