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PostgreSQL


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PostgreSQL collector can collect the running status index from PostgreSQL instance, and collect the index to Guance Cloud to help monitor and analyze various abnormal situations of PostgreSQL.

Configuration

Preconditions

  • PostgreSQL version >= 9.0
  • Create user
-- PostgreSQL >= 10
create user datakit with password '<PASSWORD>';
grant pg_monitor to datakit;
grant SELECT ON pg_stat_database to datakit;

-- PostgreSQL < 10
create user datakit with password '<PASSWORD>';
grant SELECT ON pg_stat_database to datakit;

Collector Configuration

Go to the conf.d/db directory under the DataKit installation directory, copy postgresql.conf.sample and name it postgresql.conf. Examples are as follows:

[[inputs.postgresql]]
  ## Server address
  # URI format
  # postgres://[datakit[:PASSWORD]]@localhost[/dbname]?sslmode=[disable|verify-ca|verify-full]
  # or simple string
  # host=localhost user=pqgotest password=... sslmode=... dbname=app_production

  address = "postgres://datakit:PASSWORD@localhost?sslmode=disable"

  ## Ignore databases which are gathered. Do not use with 'databases' option.
  #
  # ignored_databases = ["db1"]

  ## Specify the list of the databases to be gathered. Do not use with the 'ignored_databases' option.
  #
  # databases = ["db1"]

  ## Specify the name used as the "server" tag.
  #
  # outputaddress = "db01"

  ## Collect interval
  # Time unit: "ns", "us" (or "µs"), "ms", "s", "m", "h"
  #
  interval = "10s"

  ## Relations config
  # The list of relations/tables can be specified to track per-relation metrics. To collect relation
  # relation_name refer to the name of a relation, either relation_name or relation_regex must be set.
  # relation_regex is a regex rule, only takes effect when relation_name is not set.
  # schemas used for filtering, ignore this field when it is empty
  # relkind can be a list of the following options:
  #   r(ordinary table), i(index), S(sequence), t(TOAST table), p(partitioned table),
  #   m(materialized view), c(composite type), f(foreign table)
  #
  # [[inputs.postgresql.relations]]
  # relation_name = "<TABLE_NAME>"
  # relation_regex = "<TABLE_PATTERN>"
  # schemas = ["public"]
  # relkind = ["r", "p"]

  ## Set true to enable election
  election = true

  ## Run a custom SQL query and collect corresponding metrics.
  #
  # [[inputs.postgresql.custom_queries]]
  #   sql = '''
  #     select datname,numbackends,blks_read
  #     from pg_stat_database
  #     limit 10
  #   '''
  #   metric = "postgresql_custom_stat"
  #   tags = ["datname" ]
  #   fields = ["numbackends", "blks_read"]

  ## Log collection
  #
  # [inputs.postgresql.log]
  # files = []
  # pipeline = "postgresql.p"

  ## Custom tags
  #
  [inputs.postgresql.tags]
  # some_tag = "some_value"
  # more_tag = "some_other_value"
  # ...

After configuration, restart DataKit.

The collector can now be turned on by ConfigMap Injection Collector Configuration.

Metric

For all of the following data collections, a global tag named host is appended by default (the tag value is the host name of the DataKit), or it can be named by [[inputs.postgresql.tags]] alternative host in the configuration.

postgresql

  • tag
Tag Description
db The database name
server The server address
  • metric list
Metric Description Type Unit
active_time Time spent executing SQL statements in this database, in milliseconds. float count
blks_hit The number of times disk blocks were found in the buffer cache, preventing the need to read from the database. int count
blks_read The number of disk blocks read in this database. int count
database_size The disk space used by this database. int count
deadlocks The number of deadlocks detected in this database. int count
idle_in_transaction_time Time spent idling while in a transaction in this database, in milliseconds. float count
numbackends The number of active connections to this database. int count
session_time Time spent by database sessions in this database, in milliseconds. float count
sessions Total number of sessions established to this database. int count
sessions_abandoned Number of database sessions to this database that were terminated because connection to the client was lost. int count
sessions_fatal Number of database sessions to this database that were terminated by fatal errors. int count
sessions_killed Number of database sessions to this database that were terminated by operator intervention. int count
temp_bytes The amount of data written to temporary files by queries in this database. int count
temp_files The number of temporary files created by queries in this database. int count
tup_deleted The number of rows deleted by queries in this database. int count
tup_fetched The number of rows fetched by queries in this database. int count
tup_inserted The number of rows inserted by queries in this database. int count
tup_returned The number of rows returned by queries in this database. int count
tup_updated The number of rows updated by queries in this database. int count
wraparound The number of transactions that can occur until a transaction wraparound. float count
xact_commit The number of transactions that have been committed in this database. int count
xact_rollback The number of transactions that have been rolled back in this database. int count

postgresql_lock

  • tag
Tag Description
db The database name
locktype The lock type
mode The lock mode
schema The schema name
server The server address
table The table name
  • metric list
Metric Description Type Unit
lock_count The number of locks active for this database. int count

postgresql_index

  • tag
Tag Description
db The database name
index The index name
schema The schema name
server The server address
table The table name
  • metric list
Metric Description Type Unit
idx_scan The number of index scans initiated on this table, tagged by index. int count
idx_tup_fetch The number of live rows fetched by index scans. int count
idx_tup_read The number of index entries returned by scans on this index. int count

postgresql_replication

  • tag
Tag Description
db The database name
server The server address
  • metric list
Metric Description Type Unit
replication_delay The current replication delay in seconds. Only available with postgresql 9.1 and newer. int s
replication_delay_bytes The current replication delay in bytes. Only available with postgresql 9.2 and newer. int B

postgresql_size

  • tag
Tag Description
db The database name
schema The schema name
server The server address
table The table name
  • metric list
Metric Description Type Unit
index_size The total disk space used by indexes attached to the specified table. int B
table_size The total disk space used by the specified table. Includes TOAST, free space map, and visibility map. Excludes indexes. int B
total_size The total disk space used by the table, including indexes and TOAST data. int B

postgresql_statio

  • tag
Tag Description
db The database name
schema The schema name
server The server address
table The table name
  • metric list
Metric Description Type Unit
heap_blks_hit The number of buffer hits in this table. int count
heap_blks_read The number of disk blocks read from this table. int count
idx_blks_hit The number of buffer hits in all indexes on this table. int count
idx_blks_read The number of disk blocks read from all indexes on this table. int count
tidx_blks_hit The number of buffer hits in this table's TOAST table index. int count
tidx_blks_read The number of disk blocks read from this table's TOAST table index. int count
toast_blks_hit The number of buffer hits in this table's TOAST table. int count
toast_blks_read The number of disk blocks read from this table's TOAST table. int count

postgresql_stat

  • tag
Tag Description
db The database name
schema The schema name
server The server address
table The table name
  • metric list
Metric Description Type Unit
analyze_count The number of times this table has been manually analyzed. int count
autoanalyze_count The number of times this table has been analyzed by the autovacuum daemon. int count
autovacuum_count The number of times this table has been vacuumed by the autovacuum daemon. int count
idx_scan The number of index scans initiated on this table, tagged by index. int count
idx_tup_fetch The number of live rows fetched by index scans. int count
n_dead_tup The estimated number of dead rows. int count
n_live_tup The estimated number of live rows. int count
n_tup_del The number of rows deleted by queries in this database. int count
n_tup_hot_upd The number of rows HOT updated, meaning no separate index update was needed. int count
n_tup_ins The number of rows inserted by queries in this database. int count
n_tup_upd The number of rows updated by queries in this database. int count
seq_scan The number of sequential scans initiated on this table. int count
seq_tup_read The number of live rows fetched by sequential scans. int count
vacuum_count The number of times this table has been manually vacuumed. int count

postgresql_slru

  • tag
Tag Description
db The database name
name The name of the SLRU
server The server address
  • metric list
Metric Description Type Unit
blks_exists Number of blocks checked for existence for this SLRU (simple least-recently-used) cache. int count
blks_hit Number of times disk blocks were found already in the SLRU (simple least-recently-used.) int count
blks_read Number of disk blocks read for this SLRU (simple least-recently-used) cache. SLRU caches are created with a fixed number of pages. int count
blks_written Number of disk blocks written for this SLRU (simple least-recently-used) cache. int count
blks_zeroed Number of blocks zeroed during initializations of SLRU (simple least-recently-used) cache. int count
flushes Number of flush of dirty data for this SLRU (simple least-recently-used) cache. int count
truncates Number of truncates for this SLRU (simple least-recently-used) cache. int count

postgresql_bgwriter

  • tag
Tag Description
db The database name
server The server address
  • metric list
Metric Description Type Unit
buffers_alloc The number of buffers allocated int count
buffers_backend The number of buffers written directly by a backend. int count
buffers_backend_fsync The of times a backend had to execute its own fsync call instead of the background writer. int count
buffers_checkpoint The number of buffers written during checkpoints. int count
buffers_clean The number of buffers written by the background writer. int count
checkpoint_sync_time The total amount of checkpoint processing time spent synchronizing files to disk. float ms
checkpoint_write_time The total amount of checkpoint processing time spent writing files to disk. float ms
checkpoints_req The number of requested checkpoints that were performed. int count
checkpoints_timed The number of scheduled checkpoints that were performed. int count
maxwritten_clean The number of times the background writer stopped a cleaning scan due to writing too many buffers. int count

postgresql_connection

  • tag
Tag Description
db The database name
server The server address
  • metric list
Metric Description Type Unit
max_connections The maximum number of client connections allowed to this database. float count
percent_usage_connections The number of connections to this database as a fraction of the maximum number of allowed connections. float count

postgresql_conflict

  • tag
Tag Description
db The database name
server The server address
  • metric list
Metric Description Type Unit
confl_bufferpin Number of queries in this database that have been canceled due to pinned buffers. int count
confl_deadlock Number of queries in this database that have been canceled due to deadlocks. int count
confl_lock Number of queries in this database that have been canceled due to dropped tablespaces. This will occur when a temp_tablespace is dropped while being used on a standby. int count
confl_snapshot Number of queries in this database that have been canceled due to old snapshots. int count
confl_tablespace Number of queries in this database that have been canceled due to dropped tablespaces. This will occur when a temp_tablespace is dropped while being used on a standby. int count

postgresql_archiver

  • tag
Tag Description
db The database name
server The server address
  • metric list
Metric Description Type Unit
archived_count Number of WAL files that have been successfully archived. int count
archived_failed_count Number of failed attempts for archiving WAL files. int count

Log Collection

  • PostgreSQL logs are output to stderr by default. To open file logs, configure them in postgresql's configuration file /etc/postgresql/<VERSION>/main/postgresql.conf as follows:
logging_collector = on    # Enable log writing to files

log_directory = 'pg_log'  # Set the file storage directory, absolute path or relative path (relative PGDATA)

log_filename = 'pg.log'   # Log file name
log_statement = 'all'     # Record all queries

#log_duration = on
log_line_prefix= '%m [%p] %d [%a] %u [%h] %c ' # 日志行前缀
log_file_mode = 0644

# For Windows
#log_destination = 'eventlog'

For more configuration, please refer to the doc

  • The PostgreSQL collector does not have log collection enabled by default. You can open files in conf.d/db/postgresql.conf and write to the absolute path of the PostgreSQL log file. For example:
[[inputs.postgresql]]

  ...

  [inputs.postgresql.log]
  files = ["/tmp/pgsql/postgresql.log"]

When log collection is turned on, a log with a log source of postgresql is generated by default.

Notices:

  • Log collection only supports logs on hosts where DataKit is installed.

Log Pipeline Cut

The original log is

2021-05-31 15:23:45.110 CST [74305] test [pgAdmin 4 - DB:postgres] postgres [127.0.0.1] 60b48f01.12241 LOG:  statement:
        SELECT psd.*, 2^31 - age(datfrozenxid) as wraparound, pg_database_size(psd.datname) as pg_database_size
        FROM pg_stat_database psd
        JOIN pg_database pd ON psd.datname = pd.datname
        WHERE psd.datname not ilike 'template%'   AND psd.datname not ilike 'rdsadmin'
        AND psd.datname not ilike 'azure_maintenance'   AND psd.datname not ilike 'postgres'

Description of the cut field:

Field name Field Value Description
application_name pgAdmin 4 - DB:postgres The name of the application connecting to the current database
db_name test Database accessed
process_id 74305 The client process ID of the current connection
remote_host 127.0.0.1 Address of the client
session_id 60b48f01.12241 ID of the current session
user postgres Current Access User Name
status LOG Current log level (LOG,ERROR,FATAL,PANIC,WARNING,NOTICE,INFO)
time 1622445825110000000 Log generation time

FAQ

Missing metrics postgresql_lock, postgresql_stat, postgresql_index, postgresql_size, postgresql_statio

To report these metrics, the relations field in the configuration file needs to be enabled. If some of these metrics are partially missing, it may be because there is no data for the relevant metrics.

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