[Firebird-devel] [FB-Tracker] Created: (CORE-5434) Read-only transactions in SuperServer could not write Header and TIP pages immediately after edit
Read-only transactions in SuperServer could not write Header and TIP pages immediately after edit - Key: CORE-5434 URL: http://tracker.firebirdsql.org/browse/CORE-5434 Project: Firebird Core Issue Type: Improvement Components: Engine Reporter: Vlad Khorsun Currently engine writes contents of Header and TIP pages to disk immediately after any change (for ex. transaction start increments value of "Next transaction" counter, commit changes transaction state etc). I.e. Header and TIP pages are written to disk not waiting for commit (flush). This was done by at least two major reasons: a) safety b) in CS (and SC) page locks for Header and TIP pages is released immediately after use to avoid AST overhead In the case of many light read-only transactions these writes makes almost 100% of whole transaction time. Since read-only transactions does not change data it is safe to update on disk contents of Header and TIP pages somewhat later, for example when write transaction started (or committed) or when whole page cache is flushed at database shutdown. Note, reason (b) doesn't affect SuperServer. So, improvement is that read-only transaction will not force write of Header\TIP page content to disk immediately after change (in SS mode, of course). In the case of many light read-only transactions it gives significant performance gain. PS to address this issue in CS mode there is more complex solution, probably it will be implemented in v4 a bit later -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://tracker.firebirdsql.org/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira -- Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] Firebird 4 features
30.12.2016 17:06, Dmitry Yemanov wrote: >> Do anybody object if I try to dig a little into CORE-5064? > No, feel free. I've managed to make binary strings accessible at sql level, but found that whole engine, starting from dsc is not prepared to handle sql_sub_type and character set separately. Thus isql and API has no way to distinguish between "varchar(10) character set octets" and "varbinary(10)". Should I dig deeper and separate them everywhere through engine or to offer patch as is? -- WBR, SD. -- Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
Re: [Firebird-devel] Binary text subtype
On 2-1-2017 15:51, Dimitry Sibiryakov wrote: >Hello, All. > >What would be the right constant for binary field subtype: ttype_binary, > CS_BINARY or > dsc_text_type_fixed? They all have value 1. > As far as I can tell, you should use isc_blob_untyped, see consts_pub.h: /*/ /* Blob Subtypes */ /*/ /* types less than zero are reserved for customer use */ #define isc_blob_untyped 0 /* internal subtypes */ #define isc_blob_text 1 #define isc_blob_blr 2 #define isc_blob_acl 3 #define isc_blob_ranges 4 #define isc_blob_summary 5 #define isc_blob_format 6 #define isc_blob_tra 7 #define isc_blob_extfile 8 #define isc_blob_debug_info 9 #define isc_blob_max_predefined_subtype 10 CS_BINARY is the character set id of octets/binary, and ttype_binary as well, as it is defined as: #define ttype_binaryCS_BINARY // 1 Given the definition of dsc_text_type_fixed and his peers, I suspect this also applies to dsc_text_type_fixed. Mark -- Mark Rotteveel -- Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
