Re: pg_trgm Memory Allocation logic

Hello,

> If you manually set RPADDING 2 in trgm.h, then it will, but the
> allocation probably should use LPADDING/RPADDING to get it right, rather
> than assume the max values.

Yes you are right. For RPADDING = 2, the current formula is suitable but for
RPADDING =1, a lot of extra space is allocated.

IIUC, for each word the total number of trigrams is: (word_length + LPADDING
+ RPADDING - 2).
Also the maximum number of words a string can have is: (slen +1)/2
(considering each word has length of 1)

I think (slen + (slen + 1)/2 * (LPADDING + RPADDING - 3) + 1) allocates only
the necessary memory for different values of RPADDING.

Regards,

Beena Emerson

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Beena Emerson

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