> Fair point. Attached is v18 of the patch, after pgindent cleanup.

Here are some feedbacks to v18 patch.

1) regarding examples in create_statistics manual

Here are numbers I got. "with statistics" referrers to the case where
multivariate statistics are used.  "without statistics" referrers to the
case where multivariate statistics are not used. The numbers denote
estimated_rows/actual_rows. Thus closer to 1.0 is better. Some numbers
are shown as a fraction to avoid 0 division. In my understanding case
1, 3, 4 showed that multivariate statistics superior.

        with statistics without statistics
case1   0.98            0.01
case2   98/0            1/0
case3   1.05            0.01
case4   1/0             103/0
case5   18.50           18.33
case6   111123/0        1111123/0

2) following comments by me are not addressed in the v18 patch.

> - There's no docs for pg_mv_statistic (should be added to "49. System
>   Catalogs")
> - The word "multivariate statistics" or something like that should
>   appear in the index.
> - There are some explanation how to deal with multivariate statistics
>   in "14.1 Using Explain" and "14.2 Statistics used by the Planner"
>   section.

Best regards,
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php

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