Florian Schmitz wrote: > Hello Elke, > > this might be a possibility. How ist the SYSKEY-Colument incremented? ATM > i'm getting values like > 'FFEE00001'. > What would be the absolute maximum of different SYSKEYs?
Each table has its own syskey-numbering --> Each table starts with x'FF FE 00 00 00 00 00 01' and can go up to x'FF FE FF FF FF FF FF FF' --> during the whole lifetime of such a table 281 474 976 710 656 different syskeys can be used. Overflow of this value will not be checked. In the normal case of non-overflow, deleted syskey-values will NOT be recycled. Elke SAP Labs Berlin > > Thanks for your help. > > Flo > > > > > Zabach, Elke schrieb: > > Florian Schmitz wrote: > > > >>Hello, > >> > >> > >>i'm just thinking about different type of Primary Keys. We're actually > >>using randomly generated > >>UUIDs (GUIDs) for our "billons-of"-tables. They're stored in > VARCHAR(50)- > >>Columns and hence tend to > >>bloat space-consumption. Further i'm *guessing* they're not quite well- > >>performing concerning > >>bulk-insert and large queries. > >>How appropriate do you consider DEFAULT SERIAL for such large tables > >>(containing, or going to > >>contain billions of records)? > >>Are they're any other viable possibility for automatic created primary > >>keys? > >> > >>Thanks alot. :-) > >> > >>Flo > >> > > > > > > Did you think about our implicit primary key? > > If no user-defined primary key is given, we implicitly add a (hidden) > column syskey char (8) byte, implicitly 'incremented' for each row, thus > appending the newly inserted row to the far right end of the tree of rows > in this table (as would be done with serial,too). And this behavior is > better (performance) than receiving the next serial(sequence) value and > inserting then. > > You can ask for this implicitly key with > > 'SELECT SYSKEY,<whatever_you_like>', but SYSKEY will not be part of > > 'SELECT *' > > Does this help? > > > > Elke > > SAP Labs Berlin > > > > > >>-- > >> > >>Florian Schmitz > >> > >>______________________ > >>acardo technologies AG > >>Königswall 18a > >>44137 Dortmund > >> > >>fon: +49 (0) 2 31 / 58 44 97 - 0 > >>fax: +49 (0) 2 31 / 58 44 97 - 21 > >>mail: [EMAIL PROTECTED] > >>web: www.acardo.com > >> > >>-- > >>MaxDB Discussion Mailing List > >>For list archives: http://lists.mysql.com/maxdb > >>To unsubscribe: > http://lists.mysql.com/[EMAIL PROTECTED] > > > > > > -- MaxDB Discussion Mailing List For list archives: http://lists.mysql.com/maxdb To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
