Here is the description of the internal record format https://www.sqlite.org/fileformat.html#record_format
In comparison to a traditional C record structures it does a pretty good job when it comes to number of bytes stored. Especially if you have long string fields to accommodate insane xml content that is mostly very much shorter than the maximum size you are obliged to cater for. -----Ursprüngliche Nachricht----- Von: sqlite-users [mailto:sqlite-users-boun...@mailinglists.sqlite.org] Im Auftrag von Jay Kreibich Gesendet: Donnerstag, 06. Oktober 2016 16:49 An: SQLite mailing list <sqlite-users@mailinglists.sqlite.org> Betreff: *** suspected spam or bulk *** Re: [sqlite] Order of fields for insert On Thu, Oct 6, 2016 at 9:25 AM, Hick Gunter <h...@scigames.at> wrote: > SQLite compresses rows before storing and decompresses rows before > returning fields. BLOB fields are the most time consuming to process > and so should be placed at the end of the row. Often used fields - > i.e. (foreign) key fields - should be placed at the front of the row. > This will help most if your select field list is limited to the fields > you actually need instead of "*". > > Sorta, kinda, but not really. SQLite does not use a traditional data compression algorithm in storing row data, but it does "pack" rows into a compact format (including variable size integers). As such, a row's worth of data, as stored in the raw database, acts very similar to a compressed block of data... you have to read it from the start and can't directly jump to a field in a middle of it. This is the issue with column ordering; the data engine will only read and unpack the columns it needs, but it has to read and unpack the columns in the order they're defined until it gets all the columns it needs. This makes it generally better to put more frequently accessed and/or smaller values at the start of a row. -j _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users ___________________________________________ Gunter Hick Software Engineer Scientific Games International GmbH FN 157284 a, HG Wien Klitschgasse 2-4, A-1130 Vienna, Austria Tel: +43 1 80100 0 E-Mail: h...@scigames.at This communication (including any attachments) is intended for the use of the intended recipient(s) only and may contain information that is confidential, privileged or legally protected. Any unauthorized use or dissemination of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the sender by return e-mail message and delete all copies of the original communication. Thank you for your cooperation. _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
