> Parallel Seq Scan on data_container_archive_2022_11 dca (cost=61.36 rows=169177 width=8)|įilter: (partition_key > (CURRENT_TIMESTAMP - '2 days'::interval)) | Select id from my_foreign_table where creation_date > ' 11:20' Ĭan someone explain why there is this much difference between those queries ? What's going on under the hood ?Įxecution plan for queries without select in where clause (partition pruning, parallel scan): QUERY PLAN | Select id from my_foreign_table where creation_date > (select localtimestamp - interval '2 days') Select id from my_foreign_table where creation_date > (localtimestamp - interval '2 days') Select id from my_foreign_table where creation_date > (select current_timestamp - interval '2 days') Then I launch the same queries on same table, but through a foreign table from another database (on same instance for tests) select id from my_foreign_table where creation_date > (current_timestamp - interval '2 days') When there's no select, the plan prune the partitions not required, and do seqscan only on the remaining but it is way slower. It behave like it can't guess the outcome of the select. When there's a select in the where clause, the plan will scan all partitions. I guess there's something with type conversion. The creation_date is partition key of type timestamp (without timezone). 2.5s Plan: partition pruning parallel scan of the 5 last partitions Select id from my_table where creation_date > ' 11:20' Select id from my_table where creation_date > (select localtimestamp - interval '2 days') 7s Plan: partition pruning parallel scan of the 5 last partitions Select id from my_table where creation_date > (localtimestamp - interval '2 days') Select id from my_table where creation_date > (select current_timestamp - interval '2 days') 9s Plan: partition pruning parallel scan of 5 partitions
pgbeat is able to create table with -create-table if it doesn't exist.By default, libpq uses a database name based on the username to connect but this database might not exist so connection won't be successful. A different database name can be specified with -connect-database to connect once and create the database (ex: "postgres" or "template1"). pgbeat is able to create database with -create-database if it doesn't exist.When -user is ommited, the unix user is used. When -host is ommited, connection via unix socket is used. pgbeat relies on libpq for PostgreSQL connection.Milliseconds can be set using floating point value (ex: 0.25 for 250ms), except for -timeout where only integers are accepted. interval unit is seconds ( -interval, -recovery-interval, -timeout).pgbeat uses an identifier ( -id) associated with its timestamp so multiple daemons can run at the same time on the same instance without overlap.
#POSTGRESQL CURRENT TIMESTAMP UPDATE#
As soon as connected instance gets promoted, it will automatically start to update heartbeat. It updates a given row at a given interval of time with the current timestamp.
Pgbeat behavior is like a heartbeat system. But, what if you are using logical replication? Maybe you are restoring a backup and you want to know the real backup timestamp. When you use physical replication, you can use built-in functions like pg_last_xact_replay_timestamp() because system is always recovering. Sometimes you need to measure replication lag between a primary and one or more standbys. Periodically insert current timestamp in your PostgreSQL database
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