pg_stat_reset_subscription_stats ( oid ) void. See, One row per subscription, showing statistics about errors. Please refer to your browser's Help pages for instructions. Waiting to acquire an exclusive lock to truncate off any empty pages at the end of a table vacuumed. Waiting for logical replication remote server to change state. Waiting to retrieve messages from the shared catalog invalidation queue. In contrast, when starting from an unclean shutdown (e.g., after an immediate shutdown, a server crash, starting from a base backup, and point-in-time recovery), all statistics counters are reset. Host name of the connected client, as reported by a reverse DNS lookup of client_addr. Locks in PostgreSQL: 4. Locks in memory : Postgres Professional The track_functions parameter controls exactly which functions are tracked. Waiting for an elected Parallel Hash participant to allocate more batches. The pg_stat_wal_receiver view will contain only one row, showing statistics about the WAL receiver from that receiver's connected server. number of buffers needed by the current workload, The size of the shared buffer pool not being well balanced with the number of pages being evicted by other The pg_stat_all_tables view will contain one row for each table in the current database (including TOAST tables), showing statistics about accesses to that specific table. The optimizer also accesses indexes to check for supplied constants whose values are outside the recorded range of the optimizer statistics because the optimizer statistics might be stale. Number of transactions spilled to disk once the memory used by logical decoding to decode changes from WAL has exceeded logical_decoding_work_mem. All temporary files are counted, regardless of why the temporary file was created (e.g., sorting or hashing), and regardless of the, Total amount of data written to temporary files by queries in this database. this form Number of WAL files that have been successfully archived, Name of the WAL file most recently successfully archived, last_archived_time timestamp with time zone, Time of the most recent successful archive operation, Number of failed attempts for archiving WAL files, Name of the WAL file of the most recent failed archival operation, last_failed_time timestamp with time zone, Time of the most recent failed archival operation. Waiting for a read of a logical mapping during reorder buffer management. This counts top-level transactions only, and is not incremented for subtransactions. The total number of rows in each table, and information about vacuum and analyze actions for each table are also counted. Waiting to update limit on notification message storage. Number of decoded transactions sent to the decoding output plugin for this slot. Occasionally i noticed that in random interval of times the dbms become slow and get stuck on a few SELECT queries. Waiting for a write while initializing a new WAL file. Similarly, information about the current queries of all sessions is collected when any such information is first requested within a transaction, and the same information will be displayed throughout the transaction. It is quite possible that user has registered the tranche in one of the backends (by having allocation in dynamic shared memory) in which case other backends won't have that information, so we display extension for such cases. The pg_stat_user_indexes and pg_stat_sys_indexes views contain the same information, but filtered to only show user and system indexes respectively. PostgreSQL: Documentation: 11: 28.2. The Statistics Collector The per-index statistics are particularly useful to determine which indexes are being used and how effective they are. Waiting for a newly created timeline history file to reach durable storage. Returns the set of currently active backend ID numbers (from 1 to the number of active backends). See, One row for each table in the current database, showing statistics about accesses to that specific table. Topics Relevant engine versions Context Causes Actions Relevant engine versions Logical decoding plugins may optionally emit tracking messages; if they do not, the tracking mechanism will simply display NULL lag. Connection string used by this WAL receiver, with security-sensitive fields obfuscated. Waiting for the page number needed to continue a parallel B-tree scan to become available. Waiting to ensure that the table it has selected for a vacuum still needs vacuuming. If a backend is in the active state, it may or may not be waiting on some event. BufferPin: The server process is waiting to access to a data buffer during a period when no other process can be examining that buffer. LWLock: The backend is waiting for a lightweight lock. pg_stat_reset_replication_slot ( text ) void. This documentation is for an unsupported version of PostgreSQL. See, Only one row, showing statistics about the WAL receiver from that receiver's connected server. Waiting for a read of a timeline history file. proc: Waiting to read or update the fast-path lock information. The pg_statio_all_sequences view will contain one row for each sequence in the current database, showing statistics about I/O on that specific sequence. Waiting to access the transaction status SLRU cache. A transaction can also see its own statistics (as yet untransmitted to the collector) in the views pg_stat_xact_all_tables, pg_stat_xact_sys_tables, pg_stat_xact_user_tables, and pg_stat_xact_user_functions. Possible types are autovacuum launcher, autovacuum worker, logical replication launcher, logical replication worker, parallel worker, background writer, client backend, checkpointer, archiver, startup, walreceiver, walsender and walwriter. A backend process is waiting to associate a data block with a buffer in the shared buffer pool. Lag times work automatically for physical replication. wait_event will contain a name identifying the purpose of the lightweight lock. This has no effect in a quorum-based synchronous replication. The lag times reported in the pg_stat_replication view are measurements of the time taken for recent WAL to be written, flushed and replayed and for the sender to know about it. Waiting for SSL while attempting connection. Returns the wait event type name if this backend is currently waiting, otherwise NULL. also pending an I/O operation, The ratio between the size of the shared buffer pool (defined by the shared_buffers parameter) and the 39919 LWLock buffer_mapping 5119 Client ClientRead 3116 IO DataFileRead With C-Hash Event Count Event Type Event Name If the standby server has entirely caught up with the sending server and there is no more WAL activity, the most recently measured lag times will continue to be displayed for a short time and then show NULL. Returns the time when the backend's most recent query was started. pg_stat_reset_single_function_counters ( oid ) void. The columns wal_distance, block_distance and io_depth show current values, and the other columns show cumulative counters that can be reset with the pg_stat_reset_shared function. Waiting for a read during a file copy operation. The LWLock:BufferIO event occurs when Aurora PostgreSQL or RDS for PostgreSQL is waiting for other processes to finish their input/output (I/O) operations when concurrently trying to access a page. Normally these parameters are set in postgresql.conf so that they apply to all server processes, but it is possible to turn them on or off in individual sessions using the SET command. Priority of this standby server for being chosen as the synchronous standby in a priority-based synchronous replication. What we have discussed in this episode of 5mins of Postgres. Waiting for data to reach durable storage while adding a line to the data directory lock file. It can be joined to pg_stat_activity or pg_stat_replication on the pid column to get more details about the connection. Provide feedback Process ID of the subscription worker process, OID of the relation that the worker is synchronizing; null for the main apply worker, Last write-ahead log location received, the initial value of this field being 0, Process ID of a backend or WAL sender process, Version of SSL in use, or NULL if SSL is not in use on this connection, Name of SSL cipher in use, or NULL if SSL is not in use on this connection, Number of bits in the encryption algorithm used, or NULL if SSL is not used on this connection, True if SSL compression is in use, false if not, or NULL if SSL is not in use on this connection, Distinguished Name (DN) field from the client certificate used, or NULL if no client certificate was supplied or if SSL is not in use on this connection. Other ways of looking at the statistics can be set up by writing queries that use the same underlying statistics access functions used by the standard views shown above. Streaming only works with top-level transactions (subtransactions can't be streamed independently), so the counter is not incremented for subtransactions. Waiting for a write of logical rewrite mappings. Copyright 1996-2023 The PostgreSQL Global Development Group, PostgreSQL 15.2, 14.7, 13.10, 12.14, and 11.19 Released, 28.2.1. This counter is incremented each time a transaction is spilled, and the same transaction may be spilled multiple times. This is consistent with the goal of measuring synchronous commit and transaction visibility delays for recent write transactions. Waiting to write a protocol message to a shared message queue. This is a feature, not a bug, because it allows you to perform several queries on the statistics and correlate the results without worrying that the numbers are changing underneath you. PostgreSQL also supports reporting dynamic information about exactly what is going on in the system right now, such as the exact command currently being executed by other server processes, and which other connections exist in the system. BufferCacheHitRatio and LWLock:BufferIO wait Waiting to read or record conflicting serializable transactions. Waits for a buffer pin ( BufferPin ). might need to increase it or scale up your DB instance class. Waiting to read or update vacuum-related information for a B-tree index. If you see anything in the documentation that is not correct, does not match If state is active this field shows the currently executing query. See, Only one row, showing statistics about the WAL receiver from that receiver's connected server. backup: This WAL sender is sending a backup. Alone the requirement of separate fsyncs and everything is pretty bothersome. Waiting to read or update the state of logical replication workers. pg_stat_get_snapshot_timestamp () timestamp with time zone, Returns the timestamp of the current statistics snapshot, or NULL if no statistics snapshot has been taken.
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