[Bug 27112] select of revisions for stub history files does not explicitly order revisions
https://bugzilla.wikimedia.org/show_bug.cgi?id=27112 --- Comment #5 from Ariel T. Glenn ar...@wikimedia.org --- It's possible to request a dump by arbitrary page range (and in fact that feature is used), so no, we can't guarantee that the range will be small, unfortunately. We really only need this for the stub dumps; maybe I can tailor the queries in that special case (yuck but less yuck than temporary/filesort). -- You are receiving this mail because: You are on the CC list for the bug. ___ Wikibugs-l mailing list Wikibugs-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
[Bug 27112] select of revisions for stub history files does not explicitly order revisions
https://bugzilla.wikimedia.org/show_bug.cgi?id=27112 --- Comment #2 from Ariel T. Glenn ar...@wikimedia.org --- So does anyone on this bug have any objections if I explicitly ORDER BY rev_id ASC at the end of that query? Is that going to kill performance or break some subtle thing in the dumps as they are now? -- You are receiving this mail because: You are on the CC list for the bug. ___ Wikibugs-l mailing list Wikibugs-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
[Bug 27112] select of revisions for stub history files does not explicitly order revisions
https://bugzilla.wikimedia.org/show_bug.cgi?id=27112 --- Comment #3 from Ariel T. Glenn ar...@wikimedia.org --- the explain doesn't look good, yuck: explain SELECT * FROM `page` INNER JOIN `revision` ON ((page_id=rev_page)) WHERE page_id = 1157 AND page_id 1158 ORDER BY page_id ASC, revision.rev_id ASC; ++-+--+---++-+-+-+--+--+ | id | select_type | table| type | possible_keys | key | key_len | ref | rows | Extra | ++-+--+---++-+-+-+--+--+ | 1 | SIMPLE | page | range | PRIMARY| PRIMARY | 4 | NULL|1 | Using where; Using temporary; Using filesort | | 1 | SIMPLE | revision | ref | PRIMARY,page_timestamp | PRIMARY | 4 | elwiki.page.page_id |9 | | ++-+--+---++-+-+-+--+ Prolly need to specify which key or something in here... -- You are receiving this mail because: You are on the CC list for the bug. ___ Wikibugs-l mailing list Wikibugs-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
[Bug 27112] select of revisions for stub history files does not explicitly order revisions
https://bugzilla.wikimedia.org/show_bug.cgi?id=27112 Sean Pringle sprin...@wikimedia.org changed: What|Removed |Added CC||sprin...@wikimedia.org --- Comment #4 from Sean Pringle sprin...@wikimedia.org --- I assume the 'yuck' refers to temporary/filesort. Since the ORDER clause contains columns from both tables MySQL can't use an index for ordering. `revisions` has an index on rev_page,rev_id so doing both WHERE and ORDER on rev_* fields gives: explain SELECT * FROM `revision` JOIN `page` ON rev_page=page_id WHERE rev_page = 1157 and rev_page 1158 ORDER BY rev_page, rev_id\G *** 1. row *** id: 1 select_type: SIMPLE table: revision type: range possible_keys: PRIMARY,page_timestamp key: PRIMARY key_len: 4 ref: NULL rows: 1 Extra: Using where *** 2. row *** id: 1 select_type: SIMPLE table: page type: eq_ref possible_keys: PRIMARY key: PRIMARY key_len: 4 ref: enwiki.revision.rev_page rows: 1 Extra: Will the page_id range always be so small? Using a larger range causes the query optimizer to switch table join order and fall back on temporary/filesort again. We could force it with STRAIGHT_JOIN but at the risk of hitting far more rows... -- You are receiving this mail because: You are on the CC list for the bug. ___ Wikibugs-l mailing list Wikibugs-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
[Bug 27112] select of revisions for stub history files does not explicitly order revisions
https://bugzilla.wikimedia.org/show_bug.cgi?id=27112 Diederik van Liere dvanli...@gmail.com changed: What|Removed |Added Keywords||analytics CC||dvanli...@gmail.com -- Configure bugmail: https://bugzilla.wikimedia.org/userprefs.cgi?tab=email --- You are receiving this mail because: --- You are on the CC list for the bug. ___ Wikibugs-l mailing list Wikibugs-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
[Bug 27112] select of revisions for stub history files does not explicitly order revisions
https://bugzilla.wikimedia.org/show_bug.cgi?id=27112 --- Comment #1 from Brion Vibber br...@pobox.com 2011-02-02 19:28:14 UTC --- Note that mismatched ordering might really confuse the dump prefetching code, which IIRC assumes a consistent order of (page_id, rev_id). There are many perfectly 100% legit reasons for a later rev_id to have an earlier timestamp, chief among them: * import * restore from deletion (for things deleted prior to rev_id being stored in archive table, at least) as well as mundane things such as server clock skew. -- Configure bugmail: https://bugzilla.wikimedia.org/userprefs.cgi?tab=email --- You are receiving this mail because: --- You are on the CC list for the bug. ___ Wikibugs-l mailing list Wikibugs-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
[Bug 27112] select of revisions for stub history files does not explicitly order revisions
https://bugzilla.wikimedia.org/show_bug.cgi?id=27112 Ariel T. Glenn ar...@wikimedia.org changed: What|Removed |Added Severity|enhancement |minor -- Configure bugmail: https://bugzilla.wikimedia.org/userprefs.cgi?tab=email --- You are receiving this mail because: --- You are on the CC list for the bug. ___ Wikibugs-l mailing list Wikibugs-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
