Jens-Heiner Rechtien wrote: > SELECT count(*) > FROM spacefavorite, album_asset, albums, assetProfileLinks, > avatarCacheReferences, > cacheReferences, comment, conflicts, coreInfo, coreMD5, errors, flags, > importSource, missingBinariesOnOz, profileRegistration, quota_exceeded, > renditionRevisions, space, space_album > LIMIT 1;
The "LIMIT 1" does not have any effect because COUNT() returns only one row. > this query will busy hang and never return. It would return if you just waited long enough. This is how your query would be implemented for five tables: sqlite> explain select count(*) from a, b, c, d, e; addr opcode p1 p2 p3 p4 p5 comment ---- ------------- ---- ---- ---- ------------- -- ------------- 0 Init 0 27 0 00 Start at 27 1 Null 0 1 1 00 r[1..1]=NULL 2 OpenRead 0 3 0 0 00 root=3 iDb=0; a 3 OpenRead 1 2 0 0 00 root=2 iDb=0; b 4 OpenRead 2 4 0 0 00 root=4 iDb=0; c 5 OpenRead 3 5 0 0 00 root=5 iDb=0; d 6 OpenRead 4 6 0 0 00 root=6 iDb=0; e 7 Rewind 0 18 0 00 8 Rewind 1 17 0 00 9 Rewind 2 16 0 00 10 Rewind 3 15 0 00 11 Rewind 4 14 0 00 12 AggStep0 0 0 1 count(0) 00 accum=r[1] step(r[0]) 13 Next 4 12 0 01 14 Next 3 11 0 01 15 Next 2 10 0 01 16 Next 1 9 0 01 17 Next 0 8 0 01 18 Close 0 0 0 00 ... 23 AggFinal 1 0 0 count(0) 00 accum=r[1] N=0 24 Copy 1 2 0 00 r[2]=r[1] 25 ResultRow 2 1 0 00 output=r[2] ... Please note that "," is just the short form of "CROSS JOIN", so this query is implemented as lots of nested loops. > admittedly nonsensical You could speed up this query by deleting the contents of all tables ... Regards, Clemens _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
