On 11/29/2013 01:57 PM, Andreas Karlsson wrote: > On 11/29/2013 09:54 AM, Antonin Houska wrote: >> 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. >> >> 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(). > > For partial matches the merging is done in two steps: first a simple > union of all the streams per key and then second merging those union > streams using the consistent() function.
Yes, short after I sent my previous mail I realized that your "union" probably referred to the things that collectMatchBitmap() does. // Tony -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
