Hi, Attached is an updated version of the patch series, addressing issues pointed out by Alvaro. Let me go through the main changes:
1) I've updated / reworked the docs, updating the XML docs. There were some obsolete references to functions that got renamed later, and I've also reworked some of the user-facing docs with the aim to meet Alvaro's suggestions. I've removed the references to READMEs etc, and at this point I'm not sure I have a good idea how to improve this further ... 2) I got rid of the UPDATE_RESULT macro, along with counting the matches. Initially I intended to just expand the macro and fix the match counting (as mentioned in the FIXME), but I came to the conclusion it's not really worth the complexity. The idea was that by keeping the count of matching MCV items / histogram buckets, we can terminate early in some cases. For example when evaluating AND-clause, we can just terminate when (nmatches==0). But I have no numbers demonstrating this actually helps, and furthermore it was not implemented in histograms (well, we still counted the matches but never terminated). So I've just ripped that out and we can put it back later if needed. 3) Regarding the pg_mcv_list_items() and pg_histogram_buckets() functions, it occurred to me that people can't really inject malicious values because are no casts to the custom data types used to store MCV lists and histograms in pg_statistic_ext. The other issue was the lack of knowledge of data types for values stored in the statistics. The code used OID of the statistic to get this information (by looking at the relation). But it occurred to me this could be solved the same way the regular statistics solve this - by storing OID of the types. The anyarray does this automatically, but there's no reason we can't do that too in pg_mcv_list and pg_histogram. So I've done that, and the functions now take the custom data types instead of the OID. I've also tweaked the documentation to use the lateral syntax (good idea!) and added a new section into funcs.sgml. 4) I've merged the 0001 and 0002 patches. The 0001 was not really a bug fix, and it was a behavior change required by introducing the MCV list, so merging it seems right. 5) I've moved some changes from the histogram patch to MCV. The original patch series was structured so that it introduced some code in mcv.c and them moved it into extended_statistic.c so that it can be shared. Now it's introduced in mcv.c right away, which makes it easier to understand and reduces size of the patches. 6) I've fixed a bunch of comments, obsolete FIXMEs, etc. regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
0001-multivariate-MCV-lists.patch.gz
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0002-multivariate-histograms.patch.gz
Description: application/gzip
