Details
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Bug
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Status: Closed
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Major - P3
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Resolution: Done
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None
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None
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None
Description
Hi!
I create join cursor which include conditions on two indexes. Cursor for first condition is ordering and has strategy="default", cursor for second condition use strategy="bloom". Main table has not records, satisfying conditions, so I assume that count of reads from main table will be small, and will be caused by false-positive errors of bloom filter. But it seems that WiredTiger reads main table a lot, although I think that it is not necessary. Attached program demonstrate number of readings of index files and main table for described scenario. It has next output:
$ LD_LIBRARY_PATH=wiredtiger-2.7.0_develop ./jcursor_read_table
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Filling DB...
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total 0
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lrwx------. 1 dshkirja orcgroup 64 Mar 4 18:03 0 -> /dev/pts/1
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lrwx------. 1 dshkirja orcgroup 64 Mar 4 18:03 1 -> /dev/pts/1
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lrwx------. 1 dshkirja orcgroup 64 Mar 4 18:03 2 -> /dev/pts/1
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lrwx------. 1 dshkirja orcgroup 64 Mar 4 18:03 3 -> /home/dshkirja/issues/jcursor/jcursor_read_table.db/WiredTiger.lock
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lrwx------. 1 dshkirja orcgroup 64 Mar 4 18:03 4 -> /home/dshkirja/issues/jcursor/jcursor_read_table.db/WiredTiger.wt
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lrwx------. 1 dshkirja orcgroup 64 Mar 4 18:03 5 -> /home/dshkirja/issues/jcursor/jcursor_read_table.db/WiredTigerLAS.wt
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lrwx------. 1 dshkirja orcgroup 64 Mar 4 18:03 6 -> /home/dshkirja/issues/jcursor/jcursor_read_table.db/main_index1.wti
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lrwx------. 1 dshkirja orcgroup 64 Mar 4 18:03 7 -> /home/dshkirja/issues/jcursor/jcursor_read_table.db/main.wt
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lrwx------. 1 dshkirja orcgroup 64 Mar 4 18:03 8 -> /home/dshkirja/issues/jcursor/jcursor_read_table.db/main_index2.wti
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Reading join cursor...
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pread() fd stats:
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6: 393216
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7: 246059008
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8: 319488
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Attachments
Issue Links
- is depended on by
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SERVER-23140 WiredTiger changes for MongoDB 3.3.4
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- Closed
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- related to
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- Closed
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