From: | Sushant Sinha <sushant354(at)gmail(dot)com> |
---|---|
To: | pgsql-hackers(at)postgresql(dot)org |
Subject: | lexeme ordering in tsvector |
Date: | 2009-11-30 18:05:22 |
Message-ID: | 1259604322.3191.7.camel@dragflick |
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Lists: | pgsql-hackers |
It seems like the ordering of lexemes in tsvector has changed from 8.3
to 8.4.
For example in 8.3.1,
postgres=# select to_tsvector('english', 'quit everytime');
to_tsvector
-----------------------
'quit':1 'everytim':2
The lexemes are arranged by length and then by string comparison.
In postgres 8.4.1,
select to_tsvector('english', 'quit everytime');
to_tsvector
-----------------------
'everytim':2 'quit':1
they are arranged by strncmp and then by length.
I looked in tsvector_op.c, in the function tsCompareString, first memcmp
and then length comparison is done.
Was this change in ordering deliberate?
Wouldn't length comparison be cheaper than memcmp?
-Sushant.
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