On 11/29/2013 01:13 AM, Andreas Karlsson wrote: > When doing partial matching the code need to be able to return the union > of all TIDs in all the matching posting trees in TID order (to be able > to do AND and OR operations with multiple search keys later). It does > this by traversing them posting tree after posting tree and collecting > them all in a TIDBitmap which is later iterated over.
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I think it's not a plain union. My understanding is that - to evaluate a single key (typically array) - you first need to get all the TID streams for that key (i.e. one posting list/tree per element of the key array) and then iterate all these streams in parallel and 'merge' them using consistent() function. That's how I understand ginget.c:keyGetItem(). So the problem of partial match is (IMO) that there can be too many TID streams to merge - much more than the number of elements of the key array. // Antonin Houska (Tony) -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
