Hi.
Sometimes, if the random number generator, that PostgreSQL uses, isn't good enough, the randomly selected pages for the statistics might not be random enough.
Solaris is unknown to me. Maybe the used random number generator there isn't good enough?
Good statistics depend on good random numbers.
So, for example, if you have one million pages, but the upper bound for the random
numbers is one hundred thousand pages, the statistics might get tuned.
Or some random number generator has for example only 32000 different values.
Regards, Marko Ristola
Josh Berkus wrote:
Tom,
Any thoughts? This is really messing up query execution all across the database ...
--Josh
Here is the stats = 100 version. Notice that n_distinct has gone down.
schemaname | tablename | attname | null_frac | avg_width | n_distinct | most_common_vals
| most_common_freqs | histogram_bounds |
correlation
-------------------+------------- public | web_site_activity_fa | session_id | 0 | 8 | 96107 | {4393922,6049228,6026260,4394034,60341,4393810,2562999,2573850,3006299,4705 488,2561499,4705258,3007378,4705490,60327,60352,2560950,2567640,2569852,3006 604,4394329,2570739,2406633,2407292,3006356,4393603,4394121,6449083,2565815, 4387881,2406770,2407081,2564340,3007328,2406578,2407295,2562813,2567603,4387 835,71014,2566253,2566900,6103079,2289424,2407597,2567627,2568333,3457448,23 450,23670,60743,70739,2406818,2406852,2407511,2562816,3007446,6306095,60506, 71902,591543,1169136,1447077,2285047,2406830,2573964,6222758,61393,70955,709 86,71207,71530,262368,2289213,2406899,2567361,2775952,3006824,4387864,623982 5,6244853,6422152,1739,58600,179293,278473,488407,1896390,2286976,2407020,25 46720,2677019,2984333,3006133,3007497,3310286,3631413,3801909,4366116,438802 5}
{0.00166667,0.00146667,0.0013,0.0011,0.000933333,0.0009,0.0008,0.0008,0.000 733333,0.000733333,0.0007,0.000633333,0.0006,0.0006,0.000566667,0.000566667, 0.000566667,0.000566667,0.000566667,0.000566667,0.000566667,0.000533333,0.00 05,0.0005,0.0005,0.0005,0.0005,0.0005,0.000466667,0.000466667,0.000433333,0. 000433333,0.000433333,0.000433333,0.0004,0.0004,0.0004,0.0004,0.0004,0.00036 6667,0.000366667,0.000366667,0.000366667,0.000333333,0.000333333,0.000333333 ,0.000333333,0.000333333,0.0003,0.0003,0.0003,0.0003,0.0003,0.0003,0.0003,0. 0003,0.0003,0.0003,0.000266667,0.000266667,0.000266667,0.000266667,0.0002666 67,0.000266667,0.000266667,0.000266667,0.000266667,0.000233333,0.000233333,0 .000233333,0.000233333,0.000233333,0.000233333,0.000233333,0.000233333,0.000 233333,0.000233333,0.000233333,0.000233333,0.000233333,0.000233333,0.0002333 33,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0 002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002}
{230,58907,88648,156764,216759,240405,264601,289047,312630,339947,364452,38 6486,409427,434075,455140,475759,500086,521530,544703,680376,981066,1313419, 1712592,1860151,1882452,1905328,1927504,1948159,1970054,1990408,2014501,2038 573,2062786,2087163,2110129,2132196,2155657,2181058,2204976,2228575,2256229, 2283897,2352453,2407153,2457716,2542081,2572119,2624133,2699592,2771254,2832 224,2908151,2951500,3005088,3032889,3137244,3158685,3179395,3203681,3261587, 3304359,3325577,3566688,3621357,3645094,3718667,3740821,3762386,3783169,3804 593,3826503,3904589,3931012,3957675,4141934,4265118,4288568,4316898,4365625, 4473965,4535752,4559700,4691802,4749478,5977208,6000272,6021416,6045939,6078 912,6111900,6145155,6176422,6206627,6238291,6271270,6303067,6334117,6365200, 6395250,6424719,6888329}
| 0.41744
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