Re: URGENET: ALTER statement exectuation hangs when it is executed multiple time on a t
Dennis Wang <[email protected]>
| Newsgroups | gmane.comp.db.postgresql.interfaces |
|---|---|
| Message-ID | <[email protected]> |
Hi Tom Thank you very much for the help. > To: [email protected] > CC: [email protected] > Subject: Re: [INTERFACES] URGENET: ALTER statement exectuation hangs when it is executed multiple time on a table > Date: Thu, 10 Jan 2008 20:09:58 -0500 > From: [email protected] > > Dennis Wang writes: >> The actual PostgreSQL commands are: >> ALTER TABLE warngrid ALTER COLUMN id SET DEFAULT (nextval('warngrid_seq')* 10)+1; >> COPY warngrid FROM 'warngrid.csv' CSV HEADER; >> ALTER TABLE warngrid ALTER COLUMN id DROP DEFAULT; > >> For the first time, these operation execute fine. Then I do these steps: >> 4. delete all the records in the table >> 5. rerun the shell script to copy records. > >> Then, the ALTER statement in step 1 hanging there. > Did you do all this in one database session, or more than one? If the > latter, maybe you haven't committed the transaction that did the DELETE? I delete the records by login the database with 'psql' command, the ALTER statement is running by another process. So I guess the DELETE and ALTER are in two different session. However, the DELETE statement is a one shot command, it should commit immediately if I did not put it in a "BEGIN ... COMMIT" block. I will try that again by issue COMMIT right after the DELETE to see any difference. >> I did check the lock state of the warngrid table, it says the process created by the ALTER statement hold an 'AccessExclusiveLock' on the table. > > Did it actually *have* that lock, or was it waiting for it (granted = f > in pg_locks)? The process actually have the Lock. > regards, tom lane > > ---------------------------(end of broadcast)--------------------------- > TIP 4: Have you searched our list archives? > > http://archives.postgresql.org Regard Dennis _________________________________________________________________ New music from the Rogue Traders - listen now! http://ninemsn.com.au/share/redir/adTrack.asp?mode=click&clientID=832&referral=hotmailtaglineOct07&URL=http://music.ninemsn.com.au/roguetraders ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org