commit 1559fb54bf006a79f92eb9086c2744e84c59daf6 Author: Greg Rychlewski Date: Tue Mar 30 09:43:55 2021 -0400 Make documentation more explicit about when an ACCESS EXCLUSIVE lock is acquired. Several pages use the word "exclusive" colloquially to mean an ACCESS EXCLUSIVE lock. This can be confusing as there is another type of table lock named EXCLUSIVE. diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml index f073fbafd3..ec54885936 100644 --- a/doc/src/sgml/ddl.sgml +++ b/doc/src/sgml/ddl.sgml @@ -2630,7 +2630,7 @@ SELECT * FROM information WHERE group_id = 2 FOR UPDATE; definer function.) Also, heavy concurrent use of row share locks on the referenced table could pose a performance problem, especially if updates of it are frequent. Another solution, practical if updates of the - referenced table are infrequent, is to take an exclusive lock on the + referenced table are infrequent, is to take an ACCESS EXCLUSIVE lock on the referenced table when updating it, so that no concurrent transactions could be examining old row values. Or one could just wait for all concurrent transactions to end after committing an update of the diff --git a/doc/src/sgml/hstore.sgml b/doc/src/sgml/hstore.sgml index db5779052a..8a85798f96 100644 --- a/doc/src/sgml/hstore.sgml +++ b/doc/src/sgml/hstore.sgml @@ -926,7 +926,7 @@ UPDATE tablename SET hstorecol = hstorecol || ''; ALTER TABLE tablename ALTER hstorecol TYPE hstore USING hstorecol || ''; - The ALTER TABLE method requires an exclusive lock on the table, + The ALTER TABLE method requires an ACCESS EXCLUSIVE lock on the table, but does not result in bloating the table with old row versions. diff --git a/doc/src/sgml/indexam.sgml b/doc/src/sgml/indexam.sgml index ec5741df6d..08000d9321 100644 --- a/doc/src/sgml/indexam.sgml +++ b/doc/src/sgml/indexam.sgml @@ -980,7 +980,7 @@ amparallelrescan (IndexScanDesc scan); RowExclusiveLock when updating the index (including plain VACUUM). Since these lock types do not conflict, the access method is responsible for handling any fine-grained locking it might need. - An exclusive lock on the index as a whole will be taken only during index + An ACCESS EXCLUSIVE lock on the index as a whole will be taken only during index creation, destruction, or REINDEX. diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml index 4d8ad754f8..a7d0977a1c 100644 --- a/doc/src/sgml/maintenance.sgml +++ b/doc/src/sgml/maintenance.sgml @@ -128,7 +128,7 @@ DELETE will continue to function normally, though you will not be able to modify the definition of a table with commands such as ALTER TABLE while it is being vacuumed.) - VACUUM FULL requires exclusive lock on the table it is + VACUUM FULL requires an ACCESS EXCLUSIVE lock on the table it is working on, and therefore cannot be done in parallel with other use of the table. Generally, therefore, administrators should strive to use standard VACUUM and @@ -231,7 +231,7 @@ or one of the table-rewriting variants of ALTER TABLE. These commands rewrite an entire new copy of the table and build - new indexes for it. All these options require exclusive lock. Note that + new indexes for it. All these options require an ACCESS EXCLUSIVE lock. Note that they also temporarily use extra disk space approximately equal to the size of the table, since the old copies of the table and indexes can't be released until the new ones are complete. diff --git a/doc/src/sgml/mvcc.sgml b/doc/src/sgml/mvcc.sgml index 71dd403337..8d1e4eddc2 100644 --- a/doc/src/sgml/mvcc.sgml +++ b/doc/src/sgml/mvcc.sgml @@ -826,7 +826,7 @@ ERROR: could not serialize access due to read/write dependencies among transact tables are not dropped or modified in incompatible ways while the command executes. (For example, TRUNCATE cannot safely be executed concurrently with other operations on the same table, so it - obtains an exclusive lock on the table to enforce that.) + obtains an ACCESS EXCLUSIVE lock on the table to enforce that.) diff --git a/doc/src/sgml/pgrowlocks.sgml b/doc/src/sgml/pgrowlocks.sgml index 60e13393ea..f16fe05773 100644 --- a/doc/src/sgml/pgrowlocks.sgml +++ b/doc/src/sgml/pgrowlocks.sgml @@ -97,7 +97,7 @@ pgrowlocks(text) returns setof record - If the table as a whole is exclusive-locked by someone else, + If the someone else has an ACCESS EXCLUSIVE lock on the table, pgrowlocks will be blocked. diff --git a/doc/src/sgml/ref/drop_index.sgml b/doc/src/sgml/ref/drop_index.sgml index b6d2c2014f..b78fe89c07 100644 --- a/doc/src/sgml/ref/drop_index.sgml +++ b/doc/src/sgml/ref/drop_index.sgml @@ -45,7 +45,7 @@ DROP INDEX [ CONCURRENTLY ] [ IF EXISTS ] name Drop the index without locking out concurrent selects, inserts, updates, and deletes on the index's table. A normal DROP INDEX - acquires an exclusive lock on the table, blocking other accesses until the + acquires an ACCESS EXCLUSIVE lock on the table, blocking other accesses until the index drop can be completed. With this option, the command instead waits until conflicting transactions have completed. diff --git a/doc/src/sgml/ref/reindex.sgml b/doc/src/sgml/ref/reindex.sgml index ff4dba8c36..b0e792dde5 100644 --- a/doc/src/sgml/ref/reindex.sgml +++ b/doc/src/sgml/ref/reindex.sgml @@ -282,10 +282,10 @@ REINDEX [ ( option [, ...] ) ] { IN REINDEX is similar to a drop and recreate of the index in that the index contents are rebuilt from scratch. However, the locking considerations are rather different. REINDEX locks out writes - but not reads of the index's parent table. It also takes an exclusive lock + but not reads of the index's parent table. It also takes an ACCESS EXCLUSIVE lock on the specific index being processed, which will block reads that attempt to use that index. In contrast, DROP INDEX momentarily takes - an exclusive lock on the parent table, blocking both writes and reads. The + an ACCESS EXCLUSIVE lock on the parent table, blocking both writes and reads. The subsequent CREATE INDEX locks out writes but not reads; since the index is not there, no read will attempt to use it, meaning that there will be no blocking but reads might be forced into expensive sequential diff --git a/doc/src/sgml/ref/vacuum.sgml b/doc/src/sgml/ref/vacuum.sgml index bb1c0f8fb6..577261d6ab 100644 --- a/doc/src/sgml/ref/vacuum.sgml +++ b/doc/src/sgml/ref/vacuum.sgml @@ -83,7 +83,7 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [