Обсуждение: lexeme ordering in tsvector

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.

Sushant Sinha <sushant354@gmail.com> writes:
> Was this change in ordering deliberate?

Yes.

> Wouldn't length comparison be cheaper than memcmp?

It's not just about "cheapest" anymore, it also has to support prefix
operations.
        regards, tom lane