On Aug 22, 2013, at 7:37 AM, "Pavel Zotov (JIRA)" <trac...@firebirdsql.org> wrote:
> Wrong value of data pages average fill percent in GSTAT in case of storing > varchars that much longer than page size > --------------------------------------------------- > > ... > Page size 4096 > ODS version 12.0 > ... > T (128) > Primary pointer page: 198, Index root page: 199 > Total formats: 1, used formats: 1 > Average record length: 33037.00, total records: 1 > Average version length: 0.00, total versions: 0, max versions: 0 > Average fragment length: 4046.00, total fragments: 8, max fragments: 8 > Average unpacked length: 32771.00, compression ratio: 0.99 > Pointer pages: 1, data page slots: 1 > Data pages: 1, average fill: 17% > Primary pages: 1, full pages: 0, swept pages: 0 > Big record pages: 8 > ... Sorry to respond to the list - I'm on my iPhone and don't remember my SourceForge password. This is not a bug. Overflow (Big Record) pages are not data pages and are always filled 100%. The one data page contains the record header plus whatever data was left over when the last overflow page was filled. Big data is written back to front so the left over bit is the beginning of the string. > > > The value: "average fill: 17%" - is wrong: long string was splitted on 8 DP > and occupies in each of them almost 100% of place because of poor > compressing ratio (it was formed via gen_uuid() so RLE algorithm can not > compress such data). ------------------------------------------------------------------------------ Introducing Performance Central, a new site from SourceForge and AppDynamics. Performance Central is your source for news, insights, analysis and resources for efficient Application Performance Management. Visit us today! http://pubads.g.doubleclick.net/gampad/clk?id=48897511&iu=/4140/ostg.clktrk Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
