diff options
Diffstat (limited to 'src/include/access/nbtree.h')
| -rw-r--r-- | src/include/access/nbtree.h | 62 |
1 files changed, 27 insertions, 35 deletions
diff --git a/src/include/access/nbtree.h b/src/include/access/nbtree.h index 90a68375a2e..5fb523ecec3 100644 --- a/src/include/access/nbtree.h +++ b/src/include/access/nbtree.h @@ -925,13 +925,13 @@ typedef BTVacuumPostingData *BTVacuumPosting; * Index scans work a page at a time: we pin and read-lock the page, identify * all the matching items on the page and save them in BTScanPosData, then * release the read-lock while returning the items to the caller for - * processing. This approach minimizes lock/unlock traffic. Note that we - * keep the pin on the index page until the caller is done with all the items - * (this is needed for VACUUM synchronization, see nbtree/README). When we - * are ready to step to the next page, if the caller has told us any of the - * items were killed, we re-lock the page to mark them killed, then unlock. - * Finally we drop the pin and step to the next page in the appropriate - * direction. + * processing. This approach minimizes lock/unlock traffic. We must always + * drop the lock to make it okay for caller to process the returned items. + * Whether or not we can also release the pin during this window will vary. + * We drop the pin eagerly (when safe) to avoid blocking progress by VACUUM + * (see nbtree/README section about making concurrent TID recycling safe). + * We'll always release both the lock and the pin on the current page before + * moving on to its sibling page. * * If we are doing an index-only scan, we save the entire IndexTuple for each * matched item, otherwise only its heap TID and offset. The IndexTuples go @@ -950,28 +950,15 @@ typedef struct BTScanPosItem /* what we remember about each match */ typedef struct BTScanPosData { - Buffer buf; /* if valid, the buffer is pinned */ + Buffer buf; /* currPage buf (invalid means unpinned) */ - XLogRecPtr lsn; /* pos in the WAL stream when page was read */ + /* page details as of the saved position's call to _bt_readpage */ BlockNumber currPage; /* page referenced by items array */ - BlockNumber nextPage; /* page's right link when we scanned it */ + BlockNumber prevPage; /* currPage's left link */ + BlockNumber nextPage; /* currPage's right link */ + XLogRecPtr lsn; /* currPage's LSN */ - /* - * moreLeft and moreRight track whether we think there may be matching - * index entries to the left and right of the current page, respectively. - * We can clear the appropriate one of these flags when _bt_checkkeys() - * sets BTReadPageState.continuescan = false. - */ - bool moreLeft; - bool moreRight; - - /* - * Direction of the scan at the time that _bt_readpage was called. - * - * Used by btrestrpos to "restore" the scan's array keys by resetting each - * array to its first element's value (first in this scan direction). This - * avoids the need to directly track the array keys in btmarkpos. - */ + /* scan direction for the saved position's call to _bt_readpage */ ScanDirection dir; /* @@ -981,6 +968,13 @@ typedef struct BTScanPosData int nextTupleOffset; /* + * moreLeft and moreRight track whether we think there may be matching + * index entries to the left and right of the current page, respectively. + */ + bool moreLeft; + bool moreRight; + + /* * The items array is always ordered in index order (ie, increasing * indexoffset). When scanning backwards it is convenient to fill the * array back-to-front, so we start at the last slot and fill downwards. @@ -1021,11 +1015,8 @@ typedef BTScanPosData *BTScanPos; ) #define BTScanPosInvalidate(scanpos) \ do { \ - (scanpos).currPage = InvalidBlockNumber; \ - (scanpos).nextPage = InvalidBlockNumber; \ (scanpos).buf = InvalidBuffer; \ - (scanpos).lsn = InvalidXLogRecPtr; \ - (scanpos).nextTupleOffset = 0; \ + (scanpos).currPage = InvalidBlockNumber; \ } while (0) /* We need one of these for each equality-type SK_SEARCHARRAY scan key */ @@ -1091,7 +1082,6 @@ typedef struct BTReadPageState OffsetNumber minoff; /* Lowest non-pivot tuple's offset */ OffsetNumber maxoff; /* Highest non-pivot tuple's offset */ IndexTuple finaltup; /* Needed by scans with array keys */ - BlockNumber prev_scan_page; /* previous _bt_parallel_release block */ Page page; /* Page being read */ /* Per-tuple input parameters, set by _bt_readpage for _bt_checkkeys */ @@ -1192,12 +1182,14 @@ extern int btgettreeheight(Relation rel); /* * prototypes for internal functions in nbtree.c */ -extern bool _bt_parallel_seize(IndexScanDesc scan, BlockNumber *pageno, - bool first); -extern void _bt_parallel_release(IndexScanDesc scan, BlockNumber scan_page); +extern bool _bt_parallel_seize(IndexScanDesc scan, BlockNumber *next_scan_page, + BlockNumber *last_curr_page, bool first); +extern void _bt_parallel_release(IndexScanDesc scan, + BlockNumber next_scan_page, + BlockNumber curr_page); extern void _bt_parallel_done(IndexScanDesc scan); extern void _bt_parallel_primscan_schedule(IndexScanDesc scan, - BlockNumber prev_scan_page); + BlockNumber curr_page); /* * prototypes for functions in nbtdedup.c |