Commit50ce8ab

Neil Conway

committed

Revert changes to CREATE TRIGGER and ALTER TABLE ADD FOREIGN KEY locking,

per request from Tom.

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+13

-21

lines changed

+13

-21

lines changed

Lines changed: 4 additions & 5 deletions

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,5 @@`
`1`	`1`	`<!--`
`2`		`-$PostgreSQL: pgsql/doc/src/sgml/mvcc.sgml,v 2.48 2005/03/23 07:44:56 neilc Exp $`
	`2`	`+$PostgreSQL: pgsql/doc/src/sgml/mvcc.sgml,v 2.49 2005/03/24 00:03:18 neilc Exp $`
`3`	`3`	`-->`
`4`	`4`
`5`	`5`	`<chapter id="mvcc">`
`@@ -677,10 +677,9 @@ SELECT SUM(value) FROM mytab WHERE class = 2;`
`677`	`677`	`</para>`
`678`	`678`
`679`	`679`	`<para>`
`680`		`- Acquired by <command>CREATE TRIGGER</command> and`
`681`		`- <command>ALTER TABLE ADD FOREIGN KEY</command>. This lock`
`682`		`- mode can also be acquired on certain system catalogs in some`
`683`		`- operations.`
	`680`	`+ This lock mode is not automatically acquired on user tables by any`
	`681`	`+ <productname>PostgreSQL</productname> command. However it is`
	`682`	`+ acquired on certain system catalogs in some operations.`
`684`	`683`	`</para>`
`685`	`684`	`</listitem>`
`686`	`685`	`</varlistentry>`

Lines changed: 7 additions & 7 deletions

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.149 2005/03/23 07:44:57 neilc Exp $`
	`11`	`+ * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.150 2005/03/24 00:03:22 neilc Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -3829,13 +3829,13 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,`
`3829`	`3829`	`OidconstrOid;`
`3830`	`3830`
`3831`	`3831`	`/*`
`3832`		`- * Grabalock on the pk table, so that someone doesn't delete`
`3833`		`- * rows out from under us.We will eventually need to add triggers`
`3834`		`- *to the table, at which pointwe'll need toan ExclusiveLock --`
`3835`		`- *therefore we grab an ExclusiveLock now to prevent possible`
`3836`		`- * deadlock.`
	`3832`	`+ * Graban exclusivelock on the pk table, so that someone doesn't`
	`3833`	`+ *deleterows out from under us.(Although a lesser lock would do for`
	`3834`	`+ *that purpose,we'll needexclusive lock anywaytoadd triggers to`
	`3835`	`+ *the pk table; trying to start with a lesser lock will just create a`
	`3836`	`+ *risk ofdeadlock.)`
`3837`	`3837`	`*/`
`3838`		`-pkrel=heap_openrv(fkconstraint->pktable,ExclusiveLock);`
	`3838`	`+pkrel=heap_openrv(fkconstraint->pktable,AccessExclusiveLock);`
`3839`	`3839`
`3840`	`3840`	`/*`
`3841`	`3841`	`* Validity and permissions checks`

Lines changed: 2 additions & 9 deletions

Original file line number	Diff line number	Diff line change
`@@ -7,7 +7,7 @@`
`7`	`7`	`* Portions Copyright (c) 1994, Regents of the University of California`
`8`	`8`	`*`
`9`	`9`	`* IDENTIFICATION`
`10`		`- * $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.179 2005/03/23 07:44:57 neilc Exp $`
	`10`	`+ * $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.180 2005/03/24 00:03:26 neilc Exp $`
`11`	`11`	`*`
`12`	`12`	`*-------------------------------------------------------------------------`
`13`	`13`	`*/`
`@@ -87,14 +87,7 @@ CreateTrigger(CreateTrigStmt *stmt, bool forConstraint)`
`87`	`87`	`ObjectAddressmyself,`
`88`	`88`	`referenced;`
`89`	`89`
`90`		`-/*`
`91`		`- * We need to prevent concurrent CREATE TRIGGER commands, as well`
`92`		`- * as concurrent table modifications (INSERT, DELETE, UPDATE), so`
`93`		`- * acquire an ExclusiveLock -- it should be fine to allow SELECTs`
`94`		`- * to proceed. We could perhaps acquire ShareRowExclusiveLock, but`
`95`		`- * there seems little gain in allowing SELECT FOR UPDATE.`
`96`		`- */`
`97`		`-rel=heap_openrv(stmt->relation,ExclusiveLock);`
	`90`	`+rel=heap_openrv(stmt->relation,AccessExclusiveLock);`
`98`	`91`
`99`	`92`	`if (stmt->constrrel!=NULL)`
`100`	`93`	`constrrelid=RangeVarGetRelid(stmt->constrrel, false);`

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