Hello Richard, Thank You for the answer. We think it would make sense to reflect this rule for zeroblobs in the documentation, so other teams would save time not spending it when trying to fix bugs that don't really exist. Probably, we just missed this mentioning in the documentation, so if we did, please point us to this. Anyway, thanks a lot.
Dmitry Tsinin OS33 From: drhsql...@gmail.com [mailto:drhsql...@gmail.com] On Behalf Of Richard Hipp Sent: Tuesday, October 16, 2012 4:24 PM To: General Discussion of SQLite Database Cc: Dmitry Tsinin; Dennis Davydov; Alex Osipov; Alexander Anikin Subject: Re: [sqlite] Zeroblob initialization memory allocation issue On Mon, Oct 15, 2012 at 4:15 PM, Petr Kovalev <pkova...@os33.com<mailto:pkova...@os33.com>> wrote: Hello worldwide Sqlite team! We've found an issue caused by zeroblob initialization. Depending on the table columns creation order, zeroblob initialization causes huge memory allocation or not. Attached sample project is for Mono, but we've tried the same scenario with native methods. In first case no additional memory is allocated, but in ZeroblobFail method approx 100Mb of memory is allocated for a quick period of zeroblob creation. Could you please help to explain the behavior and provide possible workarounds? Here is quote: http://www.sqlite.org/c3ref/bind_blob.html <The sqlite3_bind_zeroblob() routine binds a BLOB of length N that is filled with zeroes. A zeroblob uses a fixed amount of memory (just an integer to hold its size) while it is being processed. Zeroblobs are intended to serve as placeholders for BLOBs whose content is later written using incremental BLOB I/O<http://www.sqlite.org/c3ref/blob_open.html> routines> In order for zeroblobs to work as above (using a fixed amount of memory no matter how big they are) all zeroblobs must be at the end of the row. In other words, the columns of the table that are receiving the zeroblobs must be the last columns in the table. If any non-zero content follows the zeroblob, then the zeroblob is expanded into a literal sequence of zero bytes, meaning memory must be allocated for the entire zeroblob. Any advice would be great. Thanks. Petr. _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org<mailto:sqlite-users@sqlite.org> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users -- D. Richard Hipp d...@sqlite.org<mailto:d...@sqlite.org> _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
