Update comments about progress reporting by index_drop

Michaël Paquier complained that index_drop is requesting progress
reporting for non-obvious reasons, so let's add a comment to explain
why.

Discussion: https://postgr.es/m/20191017010412.GH2602@paquier.xyz
This commit is contained in:
Alvaro Herrera 2019-10-18 07:18:50 -03:00
parent 3f60f690fa
commit d2efb90dba
1 changed files with 5 additions and 1 deletions

View File

@ -2142,6 +2142,10 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
* possible if one of the transactions in question is blocked trying
* to acquire an exclusive lock on our table. The lock code will
* detect deadlock and error out properly.
*
* Note: we report progress through WaitForLockers() unconditionally
* here, even though it will only be used when we're called by REINDEX
* CONCURRENTLY and not when called by DROP INDEX CONCURRENTLY.
*/
WaitForLockers(heaplocktag, AccessExclusiveLock, true);
@ -2157,7 +2161,7 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
/*
* Wait till every transaction that saw the old index state has
* finished.
* finished. See above about progress reporting.
*/
WaitForLockers(heaplocktag, AccessExclusiveLock, true);