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Commit895267a

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Remove unneeded nbtree latestRemovedXid comments.

Discussing the low level issue of nbtree VACUUM and recovery conflictsin btvacuumpage() now seems inappropriate. The same issue is discussedin nbtxlog.h, as well as in a comment block above _bt_delitems_vacuum().The comment block made more sense when it was part of a broaderdiscussion of nbtree VACUUM "pin scans". These were removed by commit9f83468.

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src/backend/access/nbtree
- nbtree.c

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`‎src/backend/access/nbtree/nbtree.c`

Lines changed: 1 addition & 26 deletions

Original file line number	Diff line number	Diff line change
`@@ -1183,12 +1183,6 @@ btvacuumpage(BTVacState *vstate, BlockNumber scanblkno)`
`1183`	`1183`	`opaque->btpo_next<scanblkno)`
`1184`	`1184`	`backtrack_to=opaque->btpo_next;`
`1185`	`1185`
`1186`		`-/*`
`1187`		`- * When each VACUUM begins, it determines an OldestXmin cutoff value.`
`1188`		`- * Tuples before the cutoff are removed by VACUUM. Scan over all`
`1189`		`- * items to see which ones need to be deleted according to cutoff`
`1190`		`- * point using callback.`
`1191`		`- */`
`1192`	`1186`	`ndeletable=0;`
`1193`	`1187`	`nupdatable=0;`
`1194`	`1188`	`minoff=P_FIRSTDATAKEY(opaque);`
`@@ -1197,6 +1191,7 @@ btvacuumpage(BTVacState *vstate, BlockNumber scanblkno)`
`1197`	`1191`	`nhtidslive=0;`
`1198`	`1192`	`if (callback)`
`1199`	`1193`	`{`
	`1194`	`+/* btbulkdelete callback tells us what to delete (or update) */`
`1200`	`1195`	`for (offnum=minoff;`
`1201`	`1196`	`offnum <=maxoff;`
`1202`	`1197`	`offnum=OffsetNumberNext(offnum))`
`@@ -1206,26 +1201,6 @@ btvacuumpage(BTVacState *vstate, BlockNumber scanblkno)`
`1206`	`1201`	`itup= (IndexTuple)PageGetItem(page,`
`1207`	`1202`	`PageGetItemId(page,offnum));`
`1208`	`1203`
`1209`		`-/*`
`1210`		`- * Hot Standby assumes that it's okay that XLOG_BTREE_VACUUM`
`1211`		`- * records do not produce their own conflicts. This is safe`
`1212`		`- * as long as the callback function only considers whether the`
`1213`		`- * index tuple refers to pre-cutoff heap tuples that were`
`1214`		`- * certainly already pruned away during VACUUM's initial heap`
`1215`		`- * scan by the time we get here. (heapam's XLOG_HEAP2_PRUNE`
`1216`		`- * records produce conflicts using a latestRemovedXid value`
`1217`		`- * for the pointed-to heap tuples, so there is no need to`
`1218`		`- * produce our own conflict now.)`
`1219`		`- *`
`1220`		`- * Backends with snapshots acquired after a VACUUM starts but`
`1221`		`- * before it finishes could have visibility cutoff with a`
`1222`		`- * later xid than VACUUM's OldestXmin cutoff. These backends`
`1223`		`- * might happen to opportunistically mark some index tuples`
`1224`		`- * LP_DEAD before we reach them, even though they may be after`
`1225`		`- * our cutoff. We don't try to kill these "extra" index`
`1226`		`- * tuples in _bt_delitems_vacuum(). This keep things simple,`
`1227`		`- * and allows us to always avoid generating our own conflicts.`
`1228`		`- */`
`1229`	`1204`	`Assert(!BTreeTupleIsPivot(itup));`
`1230`	`1205`	`if (!BTreeTupleIsPosting(itup))`
`1231`	`1206`	`{`

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Commit895267a

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`‎src/backend/access/nbtree/nbtree.c`

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