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https://issues.apache.org/jira/browse/CASSANDRA-12073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15352099#comment-15352099
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DOAN DuyHai commented on CASSANDRA-12073:
-----------------------------------------
OK, I'll update the patch with your remarks [~xedin]
> [SASI] PREFIX search on CONTAINS/NonTokenizer mode returns only partial
> results
> -------------------------------------------------------------------------------
>
> Key: CASSANDRA-12073
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12073
> Project: Cassandra
> Issue Type: Bug
> Components: CQL
> Environment: Cassandra 3.7
> Reporter: DOAN DuyHai
> Assignee: DOAN DuyHai
> Fix For: 3.x
>
> Attachments: patch_PREFIX_search_with_CONTAINS_mode.txt
>
>
> {noformat}
> cqlsh:music> CREATE TABLE music.albums (
> id uuid PRIMARY KEY,
> artist text,
> country text,
> quality text,
> status text,
> title text,
> year int
> );
> cqlsh:music> CREATE CUSTOM INDEX albums_artist_idx ON music.albums (artist)
> USING 'org.apache.cassandra.index.sasi.SASIIndex' WITH OPTIONS = {'mode':
> 'CONTAINS', 'analyzer_class':
> 'org.apache.cassandra.index.sasi.analyzer.NonTokenizingAnalyzer',
> 'case_sensitive': 'false'};
> cqlsh:music> SELECT * FROM albums WHERE artist like 'lady%' LIMIT 100;
> id | artist | country | quality
> | status | title | year
> --------------------------------------+-----------+----------------+---------+-----------+---------------------------+------
> 372bb0ab-3263-41bc-baad-bb520ddfa787 | Lady Gaga | USA | normal
> | Official | Red and Blue EP | 2006
> 1a4abbcd-b5de-4c69-a578-31231e01ff09 | Lady Gaga | Unknown | normal
> | Promotion | Poker Face | 2008
> 31f4a0dc-9efc-48bf-9f5e-bfc09af42b82 | Lady Gaga | USA | normal
> | Official | The Cherrytree Sessions | 2009
> 8ebfaebd-28d0-477d-b735-469661ce6873 | Lady Gaga | Unknown | normal
> | Official | Poker Face | 2009
> 98107d82-e0dd-46bc-a273-1577578984c7 | Lady Gaga | USA | normal
> | Official | Just Dance: The Remixes | 2008
> a76af0f2-f5c5-4306-974a-e3c17158e6c6 | Lady Gaga | Italy | normal
> | Official | The Fame | 2008
> 849ee019-8b15-4767-8660-537ab9710459 | Lady Gaga | USA | normal
> | Official | Christmas Tree | 2008
> 4bad59ac-913f-43da-9d48-89adc65453d2 | Lady Gaga | Australia | normal
> | Official | Eh Eh | 2009
> 80327731-c450-457f-bc12-0a8c21fd9c5d | Lady Gaga | USA | normal
> | Official | Just Dance Remixes Part 2 | 2008
> 3ad33659-e932-4d31-a040-acab0e23c3d4 | Lady Gaga | Unknown | normal
> | null | Just Dance | 2008
> 9adce7f6-6a1d-49fd-b8bd-8f6fac73558b | Lady Gaga | United Kingdom | normal
> | Official | Just Dance | 2009
> (11 rows)
> {noformat}
> *SASI* says that there are only 11 artists whose name starts with {{lady}}.
> However, in the data set, there are:
> * Lady Pank
> * Lady Saw
> * Lady Saw
> * Ladyhawke
> * Ladytron
> * Ladysmith Black Mambazo
> * Lady Gaga
> * Lady Sovereign
> etc ...
> By debugging the source code, the issue is in
> {{OnDiskIndex.TermIterator::computeNext()}}
> {code:java}
> for (;;)
> {
> if (currentBlock == null)
> return endOfData();
> if (offset >= 0 && offset < currentBlock.termCount())
> {
> DataTerm currentTerm = currentBlock.getTerm(nextOffset());
> if (checkLower && !e.isLowerSatisfiedBy(currentTerm))
> continue;
> // flip the flag right on the first bounds match
> // to avoid expensive comparisons
> checkLower = false;
> if (checkUpper && !e.isUpperSatisfiedBy(currentTerm))
> return endOfData();
> return currentTerm;
> }
> nextBlock();
> }
> {code}
> So the {{endOfData()}} conditions are:
> * currentBlock == null
> * checkUpper && !e.isUpperSatisfiedBy(currentTerm)
> The problem is that {{e::isUpperSatisfiedBy}} is checking not only whether
> the term match but also returns *false* when it's a *partial term* !
> {code:java}
> public boolean isUpperSatisfiedBy(OnDiskIndex.DataTerm term)
> {
> if (!hasUpper())
> return true;
> if (nonMatchingPartial(term))
> return false;
> int cmp = term.compareTo(validator, upper.value, false);
> return cmp < 0 || cmp == 0 && upper.inclusive;
> }
> {code}
> By debugging the OnDiskIndex data, I've found:
> {noformat}
> ...
> Data Term (partial ? false) : lady gaga. 0x0, TokenTree offset : 21120
> Data Term (partial ? true) : lady of bells. 0x0, TokenTree offset : 21360
> Data Term (partial ? false) : lady pank. 0x0, TokenTree offset : 21440
> ...
> {noformat}
> *lady gaga* did match but then *lady of bells* fails because it is a partial
> match. Then SASI returns {{endOfData()}} instead continuing to check *lady
> pank*
> One quick & dirty fix I've found is to add
> {{!e.nonMatchingPartial(currentTerm)}} to the *if* condition
> {code:java}
> if (checkUpper && !e.isUpperSatisfiedBy(currentTerm) &&
> !e.nonMatchingPartial(currentTerm))
> return endOfData();
> {code}
> I feel it kinda dirty and I suspect this bug to has more impact than the
> *PREFIX* case
> Wdyt [~xedin] [~beobal] [~jrwest] ?
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