Thread: Re: [PATCHES] As proposed the complete changes to pg_trigger and pg_rewrite
Re: [PATCHES] As proposed the complete changes to pg_trigger and pg_rewrite
From
Bruce Momjian
Date:
Ah, so you wait for me to go on vacation to apply it! Well, I am back now, buddy. ;-) One thing that bothers me about the patch is that it seems you are adding functionality that allows you to enable/disable trigger firing in groups, which is fine, but you are hard-coding the use of that grouping to be replication, e.g. "origin", "replica", etc. Should these designations be more generic in case there are other uses for enabling/disabling groups of triggers? --------------------------------------------------------------------------- Jan Wieck wrote: > For discussion: > > Attached is the completed patch that changes pg_trigger and extends > pg_rewrite in order to allow triggers and rules to be defined with > different, per session controllable, behaviors for replication purposes. > > This will allow replication systems like Slony-I and, as has been stated > on pgsql-hackers, other products to control the firing mechanism of > triggers and rewrite rules without modifying the system catalog directly. > > The firing mechanisms are controlled by a new superuser-only GUC > variable, session_replication_role, together with a change to > pg_trigger.tgenabled and a new column pg_rewrite.ev_enabled. Both > columns are a single char data type now (tgenabled was a bool before). > The possible values in these attributes are: > > 'O' - Trigger/Rule fires when session_replication_role is "origin" > (default) or "local". This is the default behavior. > > 'D' - Trigger/Rule is disabled and fires never > > 'A' - Trigger/Rule fires always regardless of the setting of > session_replication_role > > 'R' - Trigger/Rule fires when session_replication_role is "replica" > > The GUC variable can only be changed as long as the system does not have > any saved SPI plans. This will prevent changing the session role and > accidentally executing stored procedures or functions that have plans > cached that expand to the wrong query set due to differences in the rule > firing semantics. > > The SQL syntax for changing a triggers/rules firing semantics is > > ALTER TABLE <tabname> <when> TRIGGER|RULE <name>; > > <when> ::= ENABLE | ENABLE ALWAYS | ENABLE REPLICA | DISABLE > > psql's \d command as well as pg_dump are extended in a backward > compatible fashion. > > Any volunteers to do the corresponding documentation changes should this > patch be accepted? > -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. +
On 3/21/2007 10:24 PM, Bruce Momjian wrote: > Ah, so you wait for me to go on vacation to apply it! Well, I am back > now, buddy. ;-) Got to use my chances, don't I? :-p > > One thing that bothers me about the patch is that it seems you are > adding functionality that allows you to enable/disable trigger firing in > groups, which is fine, but you are hard-coding the use of that grouping > to be replication, e.g. "origin", "replica", etc. > > Should these designations be more generic in case there are other uses > for enabling/disabling groups of triggers? That would be fine with me, I just wasn't able to come up with any sensible naming scheme other than replication related. Can you? Jan > > --------------------------------------------------------------------------- > > Jan Wieck wrote: >> For discussion: >> >> Attached is the completed patch that changes pg_trigger and extends >> pg_rewrite in order to allow triggers and rules to be defined with >> different, per session controllable, behaviors for replication purposes. >> >> This will allow replication systems like Slony-I and, as has been stated >> on pgsql-hackers, other products to control the firing mechanism of >> triggers and rewrite rules without modifying the system catalog directly. >> >> The firing mechanisms are controlled by a new superuser-only GUC >> variable, session_replication_role, together with a change to >> pg_trigger.tgenabled and a new column pg_rewrite.ev_enabled. Both >> columns are a single char data type now (tgenabled was a bool before). >> The possible values in these attributes are: >> >> 'O' - Trigger/Rule fires when session_replication_role is "origin" >> (default) or "local". This is the default behavior. >> >> 'D' - Trigger/Rule is disabled and fires never >> >> 'A' - Trigger/Rule fires always regardless of the setting of >> session_replication_role >> >> 'R' - Trigger/Rule fires when session_replication_role is "replica" >> >> The GUC variable can only be changed as long as the system does not have >> any saved SPI plans. This will prevent changing the session role and >> accidentally executing stored procedures or functions that have plans >> cached that expand to the wrong query set due to differences in the rule >> firing semantics. >> >> The SQL syntax for changing a triggers/rules firing semantics is >> >> ALTER TABLE <tabname> <when> TRIGGER|RULE <name>; >> >> <when> ::= ENABLE | ENABLE ALWAYS | ENABLE REPLICA | DISABLE >> >> psql's \d command as well as pg_dump are extended in a backward >> compatible fashion. >> >> Any volunteers to do the corresponding documentation changes should this >> patch be accepted? >> > -- #======================================================================# # It's easier to get forgiveness for being wrong than for being right. # # Let's break this rule - forgive me. # #================================================== JanWieck@Yahoo.com #
Re: [PATCHES] As proposed the complete changes to pg_trigger and pg_rewrite
From
Bruce Momjian
Date:
Jan Wieck wrote: > On 3/21/2007 10:24 PM, Bruce Momjian wrote: > > Ah, so you wait for me to go on vacation to apply it! Well, I am back > > now, buddy. ;-) > > Got to use my chances, don't I? :-p > > > > > One thing that bothers me about the patch is that it seems you are > > adding functionality that allows you to enable/disable trigger firing in > > groups, which is fine, but you are hard-coding the use of that grouping > > to be replication, e.g. "origin", "replica", etc. > > > > Should these designations be more generic in case there are other uses > > for enabling/disabling groups of triggers? > > That would be fine with me, I just wasn't able to come up with any > sensible naming scheme other than replication related. Can you? The best I could think of would be to create numbered groups of triggers, but because I can't think of any use for that, and no one else has, I think the patch is fine unchanged. --------------------------------------------------------------------------- > > Jan Wieck wrote: > >> For discussion: > >> > >> Attached is the completed patch that changes pg_trigger and extends > >> pg_rewrite in order to allow triggers and rules to be defined with > >> different, per session controllable, behaviors for replication purposes. > >> > >> This will allow replication systems like Slony-I and, as has been stated > >> on pgsql-hackers, other products to control the firing mechanism of > >> triggers and rewrite rules without modifying the system catalog directly. > >> > >> The firing mechanisms are controlled by a new superuser-only GUC > >> variable, session_replication_role, together with a change to > >> pg_trigger.tgenabled and a new column pg_rewrite.ev_enabled. Both > >> columns are a single char data type now (tgenabled was a bool before). > >> The possible values in these attributes are: > >> > >> 'O' - Trigger/Rule fires when session_replication_role is "origin" > >> (default) or "local". This is the default behavior. > >> > >> 'D' - Trigger/Rule is disabled and fires never > >> > >> 'A' - Trigger/Rule fires always regardless of the setting of > >> session_replication_role > >> > >> 'R' - Trigger/Rule fires when session_replication_role is "replica" > >> > >> The GUC variable can only be changed as long as the system does not have > >> any saved SPI plans. This will prevent changing the session role and > >> accidentally executing stored procedures or functions that have plans > >> cached that expand to the wrong query set due to differences in the rule > >> firing semantics. > >> > >> The SQL syntax for changing a triggers/rules firing semantics is > >> > >> ALTER TABLE <tabname> <when> TRIGGER|RULE <name>; > >> > >> <when> ::= ENABLE | ENABLE ALWAYS | ENABLE REPLICA | DISABLE > >> > >> psql's \d command as well as pg_dump are extended in a backward > >> compatible fashion. > >> > >> Any volunteers to do the corresponding documentation changes should this > >> patch be accepted? > >> > > > > > -- > #======================================================================# > # It's easier to get forgiveness for being wrong than for being right. # > # Let's break this rule - forgive me. # > #================================================== JanWieck@Yahoo.com # -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. +
Re: Re: [PATCHES] As proposed the complete changes to pg_trigger and pg_rewrite
From
alfranio correia junior
Date:
>>> >>> Should these designations be more generic in case there are other uses >>> for enabling/disabling groups of triggers? >> That would be fine with me, I just wasn't able to come up with any >> sensible naming scheme other than replication related. Can you? > > The best I could think of would be to create numbered groups of > triggers, but because I can't think of any use for that, and no one else > has, I think the patch is fine unchanged. Instead of numbering, why don't you use names ? ------------------------------------------------------------------------ I did a similar patch a couple of years ago, but I put it away as it required modifications to the database catalog. I am glad to hear that modifications to make replication easier on top of PostgreSQL are being made. Do you have any plans in introducing flags for other types of constraints and even sequences. Such modifications would be very useful for replication. Best regards, Alfranio.