[Building Sakai] MSGCNTR Forums mysql picks a slow query plan over a faster query plan
Earle Nietzel
earle.nietzel at gmail.com
Wed Sep 7 07:33:14 PDT 2011
Hi Bryan,
(I had also included it the original post)
The only thing I added was the straight_join (MySQL specific). Take a look
last query seems to be the better performer.
Original query:
select count(*) as col_0_0_
from MFR_TOPIC_T topicimpl0_
inner join MFR_OPEN_FORUM_T openforumi2_ on
topicimpl0_.of_surrogateKey=openforumi2_.ID
inner join MFR_AREA_T areaimpl3_ on openforumi2_.surrogateKey=areaimpl3_.ID
inner join MFR_MEMBERSHIP_ITEM_T membership4_ on
topicimpl0_.ID=membership4_.t_surrogateKey,
MFR_PERMISSION_LEVEL_T permission1_
where areaimpl3_.CONTEXT_ID='517f8f28-f68e-42ee-b168-919a06f82229'
and topicimpl0_.MODERATED=1
and (membership4_.NAME in ('Student' , 'MATH_111L_114_11F'))
and permission1_.MODERATE_POSTINGS=1
and permission1_.TYPE_UUID!='00000000-0000-0000-7777-000000000000'
and permission1_.NAME=membership4_.PERMISSION_LEVEL_NAME
Query with straight_join added:
select straight_join count(*) as col_0_0_
from MFR_TOPIC_T topicimpl0_
inner join MFR_OPEN_FORUM_T openforumi2_ on
topicimpl0_.of_surrogateKey=openforumi2_.ID
inner join MFR_AREA_T areaimpl3_ on openforumi2_.surrogateKey=areaimpl3_.ID
inner join MFR_MEMBERSHIP_ITEM_T membership4_ on
topicimpl0_.ID=membership4_.t_surrogateKey,
MFR_PERMISSION_LEVEL_T permission1_
where areaimpl3_.CONTEXT_ID='517f8f28-f68e-42ee-b168-919a06f82229'
and topicimpl0_.MODERATED=1
and (membership4_.NAME in ('Student' , 'MATH_111L_114_11F'))
and permission1_.MODERATE_POSTINGS=1
and permission1_.TYPE_UUID!='00000000-0000-0000-7777-000000000000'
and permission1_.NAME=membership4_.PERMISSION_LEVEL_NAME
This query with a straight_join seems to out perform the query above and its
query plan matches that of the original query when the original runs well:
(I would recommend this query)
select straight_join count(topicimpl0_.ID) as col_0_0_
from MFR_AREA_T areaimpl3_
inner join MFR_OPEN_FORUM_T openforumi2_ on
openforumi2_.surrogateKey=areaimpl3_.ID
inner join MFR_TOPIC_T topicimpl0_ on
topicimpl0_.of_surrogateKey=openforumi2_.ID
inner join MFR_MEMBERSHIP_ITEM_T membership4_ on
topicimpl0_.ID=membership4_.t_surrogateKey,
MFR_PERMISSION_LEVEL_T permission1_
where areaimpl3_.CONTEXT_ID='517f8f28-f68e-42ee-b168-919a06f82229'
and topicimpl0_.MODERATED=1
and (membership4_.NAME in ('Student' , 'MATH_111L_114_11F'))
and permission1_.MODERATE_POSTINGS=1
and permission1_.TYPE_UUID!='00000000-0000-0000-7777-000000000000'
and permission1_.NAME=membership4_.PERMISSION_LEVEL_NAME
Earle
On Wed, Sep 7, 2011 at 8:12 AM, Bryan Holladay <holladay at longsight.com>wrote:
> Earle,
>
> Could you send me both queries:
>
> 1) the slow query that Sakai uses (the actual SQL query, not the
> hibernate query. You can get this by setting hibernate.show_sql=true
> in the sakai.properties (DO NOT SET THIS IN PRD!!!) and watch the
> logs).
>
> 2) your new join query to resolve this (actual SQL)
>
> Then I can look at the query plans on my local machine to see how the
> index's pan out.
>
> Thanks,
> Bryan
>
> On Tue, Sep 6, 2011 at 5:48 PM, Earle Nietzel <earle.nietzel at gmail.com>
> wrote:
> > Hi Bryan.
> >
> > I have included the create statements from our DB (see below inline).
> >
> > Everything matches up except we have a few additional Foreign Keys
> > while you didn't mention the other tables I am assuming that they are
> > fine.
> >
> > On the side I did a hbm2ddl and it seems that more indexes are
> > definitely created according to hibernate.
> >
> > I realize this issue is a bit strange but I don't believe there to be
> > a problem with sakai but rather mysql.
> >
> > So I suggested a workaround for mysql using a straight_join.
> >
> > I am not sure if that is the best idea or maybe rework the query so
> > that mysql doesn't get into a situation of picking a bad query plan.
> >
> > Earle
> >
> > BTW We are using mysql-5.1.52-1.el6_0.1.x86_64
> >
> > On Tue, Sep 6, 2011 at 8:24 AM, Bryan Holladay <holladay at longsight.com>
> wrote:
> >>
> >> What index's do you have set? This has a huge effect on query plans
> >> and most people have too many index's set. Make sure you only have
> >> these index's and then look at the query plan:
> >>
> >> CREATE INDEX MFR_UNREAD_STATUS_I2 USING BTREE
> >> ON MFR_UNREAD_STATUS_T(MESSAGE_C, USER_C, READ_C);
> >>
> >> CREATE INDEX MFR_UNREAD_STATUS_I1 USING BTREE
> >> ON MFR_UNREAD_STATUS_T(TOPIC_C, MESSAGE_C, USER_C, READ_C);
> >>
> >> CREATE UNIQUE INDEX PRIMARY USING BTREE
> >> ON MFR_UNREAD_STATUS_T(ID);
> >>
> >> ALTER TABLE MFR_UNREAD_STATUS_T
> >> ADD CONSTRAINT TOPIC_C
> >> UNIQUE (TOPIC_C, MESSAGE_C, USER_C);
> >
> > | MFR_UNREAD_STATUS_T | CREATE TABLE `mfr_unread_status_t` (
> > `ID` bigint(20) NOT NULL AUTO_INCREMENT,
> > `VERSION` int(11) NOT NULL,
> > `TOPIC_C` bigint(20) NOT NULL,
> > `MESSAGE_C` bigint(20) NOT NULL,
> > `USER_C` varchar(255) NOT NULL,
> > `READ_C` bit(1) NOT NULL,
> > PRIMARY KEY (`ID`),
> > UNIQUE KEY `TOPIC_C` (`TOPIC_C`,`MESSAGE_C`,`USER_C`),
> > KEY `MFR_UNREAD_STATUS_I2` (`MESSAGE_C`,`USER_C`,`READ_C`),
> > KEY `MFR_UNREAD_STATUS_I1` (`TOPIC_C`,`MESSAGE_C`,`USER_C`,`READ_C`)
> > USING BTREE
> > ) ENGINE=InnoDB AUTO_INCREMENT=5750248 DEFAULT CHARSET=utf8 |
> >
> >
> >>
> >> ALTER TABLE MFR_MESSAGE_T
> >> ADD CONSTRAINT FK80C1A316A2D0BE7B
> >> FOREIGN KEY(surrogateKey)
> >> REFERENCES MFR_TOPIC_T(ID);
> >>
> >
> > | MFR_MESSAGE_T | CREATE TABLE `mfr_message_t` (
> > `ID` bigint(20) NOT NULL AUTO_INCREMENT,
> > `MESSAGE_DTYPE` varchar(2) NOT NULL,
> > `VERSION` int(11) NOT NULL,
> > `UUID` varchar(36) NOT NULL,
> > `CREATED` datetime NOT NULL,
> > `CREATED_BY` varchar(36) NOT NULL,
> > `MODIFIED` datetime NOT NULL,
> > `MODIFIED_BY` varchar(36) NOT NULL,
> > `TITLE` varchar(255) NOT NULL,
> > `BODY` text,
> > `AUTHOR` varchar(255) NOT NULL,
> > `HAS_ATTACHMENTS` bit(1) NOT NULL,
> > `GRADEASSIGNMENTNAME` varchar(255) DEFAULT NULL,
> > `LABEL` varchar(255) DEFAULT NULL,
> > `IN_REPLY_TO` bigint(20) DEFAULT NULL,
> > `TYPE_UUID` varchar(36) NOT NULL,
> > `APPROVED` bit(1) DEFAULT NULL,
> > `DRAFT` bit(1) NOT NULL,
> > `surrogateKey` bigint(20) DEFAULT NULL,
> > `EXTERNAL_EMAIL` bit(1) DEFAULT NULL,
> > `EXTERNAL_EMAIL_ADDRESS` varchar(255) DEFAULT NULL,
> > `RECIPIENTS_AS_TEXT` text,
> > `DELETED` bit(1) NOT NULL DEFAULT b'0',
> > `NUM_READERS` int(11) DEFAULT NULL,
> > `THREADID` bigint(20) DEFAULT NULL,
> > `LASTTHREADATE` datetime DEFAULT NULL,
> > `LASTTHREAPOST` bigint(20) DEFAULT NULL,
> > PRIMARY KEY (`ID`),
> > KEY `FK80C1A31650339D56` (`IN_REPLY_TO`),
> > KEY `FK80C1A316A2D0BE7B` (`surrogateKey`),
> > KEY `MFR_MESSAGE_DELETED_I` (`DELETED`),
> > KEY `MFR_MESSAGE_T_IN_REPLY_TO_I` (`IN_REPLY_TO`),
> > KEY `mfrmessageindex2` (`CREATED_BY`),
> > CONSTRAINT `FK80C1A31650339D56` FOREIGN KEY (`IN_REPLY_TO`)
> > REFERENCES `mfr_message_t` (`ID`),
> > CONSTRAINT `FK80C1A316A2D0BE7B` FOREIGN KEY (`surrogateKey`)
> > REFERENCES `mfr_topic_t` (`ID`)
> > ) ENGINE=InnoDB AUTO_INCREMENT=1196102 DEFAULT CHARSET=utf8 |
> >
> >
> >>
> >> ALTER TABLE MFR_TOPIC_T
> >> ADD CONSTRAINT FK863DC0BE74C7E92B
> >> FOREIGN KEY(of_surrogateKey)
> >> REFERENCES MFR_OPEN_FORUM_T(ID);
> >>
> >
> > | MFR_TOPIC_T | CREATE TABLE `mfr_topic_t` (
> > `ID` bigint(20) NOT NULL AUTO_INCREMENT,
> > `TOPIC_DTYPE` varchar(2) NOT NULL,
> > `VERSION` int(11) NOT NULL,
> > `UUID` varchar(36) NOT NULL,
> > `CREATED` datetime NOT NULL,
> > `CREATED_BY` varchar(36) NOT NULL,
> > `MODIFIED` datetime NOT NULL,
> > `MODIFIED_BY` varchar(36) NOT NULL,
> > `DEFAULTASSIGNNAME` varchar(255) DEFAULT NULL,
> > `TITLE` varchar(255) NOT NULL,
> > `SHORT_DESCRIPTION` varchar(255) DEFAULT NULL,
> > `EXTENDED_DESCRIPTION` text,
> > `MODERATED` bit(1) NOT NULL,
> > `MUTABLE` bit(1) NOT NULL,
> > `SORT_INDEX` int(11) NOT NULL,
> > `TYPE_UUID` varchar(36) NOT NULL,
> > `of_surrogateKey` bigint(20) DEFAULT NULL,
> > `pf_surrogateKey` bigint(20) DEFAULT NULL,
> > `USER_ID` varchar(255) DEFAULT NULL,
> > `CONTEXT_ID` varchar(36) DEFAULT NULL,
> > `pt_surrogateKey` bigint(20) DEFAULT NULL,
> > `LOCKED` bit(1) DEFAULT NULL,
> > `DRAFT` bit(1) DEFAULT NULL,
> > `CONFIDENTIAL_RESPONSES` bit(1) DEFAULT NULL,
> > `MUST_RESPOND_BEFORE_READING` bit(1) DEFAULT NULL,
> > `HOUR_BEFORE_RESPONSES_VISIBLE` int(11) DEFAULT NULL,
> > `AUTO_MARK_THREADS_READ` bit(1) NOT NULL,
> > `AVAILABILITY_RESTRICTED` bit(1) NOT NULL DEFAULT b'0',
> > `AVAILABILITY` bit(1) NOT NULL DEFAULT b'1',
> > `OPEN_DATE` datetime DEFAULT NULL,
> > `CLOSE_DATE` datetime DEFAULT NULL,
> > PRIMARY KEY (`ID`),
> > KEY `FK863DC0BE82FAB29` (`pf_surrogateKey`),
> > KEY `FK863DC0BEFF3B3AE9` (`pt_surrogateKey`),
> > KEY `FK863DC0BE74C7E92B` (`of_surrogateKey`),
> > KEY `MFR_TOPIC_T_UUID_I` (`UUID`),
> > CONSTRAINT `FK863DC0BE74C7E92B` FOREIGN KEY (`of_surrogateKey`)
> > REFERENCES `mfr_open_forum_t` (`ID`),
> > CONSTRAINT `FK863DC0BE82FAB29` FOREIGN KEY (`pf_surrogateKey`)
> > REFERENCES `mfr_private_forum_t` (`ID`),
> > CONSTRAINT `FK863DC0BEFF3B3AE9` FOREIGN KEY (`pt_surrogateKey`)
> > REFERENCES `mfr_topic_t` (`ID`)
> > ) ENGINE=InnoDB AUTO_INCREMENT=574313 DEFAULT CHARSET=utf8 |
> >
> >
> >>
> >> ALTER TABLE MFR_OPEN_FORUM_T
> >> ADD CONSTRAINT FKC17608478B5E2A2F
> >> FOREIGN KEY(surrogateKey)
> >> REFERENCES MFR_AREA_T(ID);
> >>
> >
> > | MFR_OPEN_FORUM_T | CREATE TABLE `mfr_open_forum_t` (
> > `ID` bigint(20) NOT NULL AUTO_INCREMENT,
> > `FORUM_DTYPE` varchar(2) NOT NULL,
> > `VERSION` int(11) NOT NULL,
> > `UUID` varchar(36) NOT NULL,
> > `CREATED` datetime NOT NULL,
> > `CREATED_BY` varchar(36) NOT NULL,
> > `MODIFIED` datetime NOT NULL,
> > `MODIFIED_BY` varchar(36) NOT NULL,
> > `DEFAULTASSIGNNAME` varchar(255) DEFAULT NULL,
> > `TITLE` varchar(255) NOT NULL,
> > `SHORT_DESCRIPTION` varchar(255) DEFAULT NULL,
> > `EXTENDED_DESCRIPTION` text,
> > `TYPE_UUID` varchar(36) NOT NULL,
> > `SORT_INDEX` int(11) NOT NULL,
> > `LOCKED` bit(1) NOT NULL,
> > `DRAFT` bit(1) DEFAULT NULL,
> > `surrogateKey` bigint(20) DEFAULT NULL,
> > `MODERATED` bit(1) NOT NULL,
> > `AUTO_MARK_THREADS_READ` bit(1) NOT NULL,
> > `AVAILABILITY_RESTRICTED` bit(1) NOT NULL DEFAULT b'0',
> > `AVAILABILITY` bit(1) NOT NULL DEFAULT b'1',
> > `OPEN_DATE` datetime DEFAULT NULL,
> > `CLOSE_DATE` datetime DEFAULT NULL,
> > PRIMARY KEY (`ID`),
> > KEY `FKC17608478B5E2A2F` (`surrogateKey`),
> > CONSTRAINT `FKC17608478B5E2A2F` FOREIGN KEY (`surrogateKey`)
> > REFERENCES `mfr_area_t` (`ID`)
> > ) ENGINE=InnoDB AUTO_INCREMENT=17835 DEFAULT CHARSET=utf8 |
> >
> >
> >>
> >> ALTER TABLE MFR_AREA_T
> >> ADD CONSTRAINT MFR_AREA_CONTEXT_UUID_UNIQUE
> >> UNIQUE (CONTEXT_ID, TYPE_UUID);
> >>
> >
> > | MFR_AREA_T | CREATE TABLE `mfr_area_t` (
> > `ID` bigint(20) NOT NULL AUTO_INCREMENT,
> > `VERSION` int(11) NOT NULL,
> > `UUID` varchar(36) NOT NULL,
> > `CREATED` datetime NOT NULL,
> > `CREATED_BY` varchar(36) NOT NULL,
> > `MODIFIED` datetime NOT NULL,
> > `MODIFIED_BY` varchar(36) NOT NULL,
> > `CONTEXT_ID` varchar(255) NOT NULL,
> > `NAME` varchar(255) NOT NULL,
> > `HIDDEN` bit(1) NOT NULL,
> > `TYPE_UUID` varchar(36) NOT NULL,
> > `ENABLED` bit(1) NOT NULL,
> > `LOCKED` bit(1) NOT NULL,
> > `MODERATED` bit(1) NOT NULL,
> > `SENDEMAILOUT` bit(1) NOT NULL,
> > `AUTO_MARK_THREADS_READ` bit(1) NOT NULL,
> > `AVAILABILITY_RESTRICTED` bit(1) NOT NULL DEFAULT b'0',
> > `AVAILABILITY` bit(1) NOT NULL DEFAULT b'1',
> > `OPEN_DATE` datetime DEFAULT NULL,
> > `CLOSE_DATE` datetime DEFAULT NULL,
> > PRIMARY KEY (`ID`),
> > UNIQUE KEY `MFR_AREA_CONTEXT_UUID_UNIQUE` (`CONTEXT_ID`,`TYPE_UUID`),
> > KEY `CONTEXT_ID` (`CONTEXT_ID`(20))
> > ) ENGINE=InnoDB AUTO_INCREMENT=12227 DEFAULT CHARSET=utf8 |
> >
> >
> >>
> >> On Fri, Sep 2, 2011 at 4:15 PM, Earle Nietzel <earle.nietzel at gmail.com>
> wrote:
> >> > Here is the version from the pom:
> >> >
> >> > <name>Sakai Message Center Base POM</name>
> >> > <groupId>org.sakaiproject.msgcntr</groupId>
> >> > <version>2.8.0-rc04</version>
> >> > <artifactId>msgcntr</artifactId>
> >> > <packaging>pom</packaging>
> >> >
> >> > Earle
> >> >
> >> > On Fri, Sep 2, 2011 at 4:08 PM, Sam Ottenhoff <
> ottenhoff at longsight.com>
> >> > wrote:
> >> >>
> >> >> What version of MsgCntr? Do you see the same issue on trunk MsgCntr?
> >> >> Note that MsgCntr 2.7.0 has major performance issues and should not
> be run
> >> >> in any type of serious production environment.
> >> >> --Sam
> >> >>
> >> >> On Fri, Sep 2, 2011 at 3:51 PM, Earle Nietzel <
> earle.nietzel at gmail.com>
> >> >> wrote:
> >> >>>
> >> >>> Hello everyone,
> >> >>>
> >> >>> Got a bit of an issue here with forums and a particular query that
> mysql
> >> >>> is coming up with different query plans. Depending on which one it
> selects
> >> >>> it can take a significant amount of time to complete.
> >> >>>
> >> >>> The hql in question (added from MSGCNTR-364):
> >> >>>
> >> >>> <query
> >> >>>
> name="findNumModeratedTopicsForSiteByUserByMembershipWithPermissionLevelName">
> >> >>> <![CDATA[select count(*) from
> >> >>> org.sakaiproject.component.app.messageforums.dao.hibernate.TopicImpl
> as
> >> >>> topic,
> >> >>>
> >> >>>
> org.sakaiproject.component.app.messageforums.dao.hibernate.PermissionLevelImpl
> >> >>> as pl
> >> >>> join topic.openForum as forum
> >> >>> join forum.area as area
> >> >>> join topic.membershipItemSet as membershipItem
> >> >>> where area.contextId = :contextId and
> >> >>> topic.moderated = true and
> >> >>> membershipItem.name in ( :membershipList ) and
> >> >>> pl.moderatePostings = true and
> >> >>> (pl.typeUuid != :customTypeUuid and
> >> >>> pl.name = membershipItem.permissionLevelName)
> >> >>> ]]>
> >> >>> </query>
> >> >>>
> >> >>> Which then is compiled into this SQL:
> >> >>>
> >> >>> select count(*) as col_0_0_
> >> >>> from MFR_TOPIC_T topicimpl0_
> >> >>> inner join MFR_OPEN_FORUM_T openforumi2_ on
> >> >>> topicimpl0_.of_surrogateKey=openforumi2_.ID
> >> >>> inner join MFR_AREA_T areaimpl3_ on
> >> >>> openforumi2_.surrogateKey=areaimpl3_.ID
> >> >>> inner join MFR_MEMBERSHIP_ITEM_T membership4_ on
> >> >>> topicimpl0_.ID=membership4_.t_surrogateKey,
> >> >>> MFR_PERMISSION_LEVEL_T permission1_
> >> >>> where areaimpl3_.CONTEXT_ID='517f8f28-f68e-42ee-b168-919a06f82229'
> >> >>> and topicimpl0_.MODERATED=1
> >> >>> and (membership4_.NAME in ('Student' , 'MATH_111L_114_11F'))
> >> >>> and permission1_.MODERATE_POSTINGS=1
> >> >>> and permission1_.TYPE_UUID!='00000000-0000-0000-7777-000000000000'
> >> >>> and permission1_.NAME=membership4_.PERMISSION_LEVEL_NAME
> >> >>>
> >> >>> The efficient query plan looks like:
> >> >>>
> >> >>>
> +----+-------------+--------------+------+-------------------------------------------------+------------------------------+---------+-------------------------------------------+-------+--------------------------+
> >> >>> | id | select_type | table | type |
> >> >>> possible_keys |
> >> >>> key | key_len |
> >> >>> ref | rows | Extra
> >> >>> |
> >> >>>
> >> >>>
> +----+-------------+--------------+------+-------------------------------------------------+------------------------------+---------+-------------------------------------------+-------+--------------------------+
> >> >>> | 1 | SIMPLE | areaimpl3_ | ref |
> >> >>> PRIMARY,MFR_AREA_CONTEXT_UUID_UNIQUE,CONTEXT_ID |
> >> >>> MFR_AREA_CONTEXT_UUID_UNIQUE | 767 |
> >> >>> const | 2 | Using where;
> Using index
> >> >>> |
> >> >>> | 1 | SIMPLE | openforumi2_ | ref |
> >> >>> PRIMARY,FKC17608478B5E2A2F |
> >> >>> FKC17608478B5E2A2F | 9 |
> >> >>> ilearn.areaimpl3_.ID | 3 | Using where;
> Using index
> >> >>> |
> >> >>> | 1 | SIMPLE | topicimpl0_ | ref |
> >> >>> PRIMARY,FK863DC0BE74C7E92B |
> >> >>> FK863DC0BE74C7E92B | 9 |
> >> >>> ilearn.openforumi2_.ID | 35 | Using where
> >> >>> |
> >> >>> | 1 | SIMPLE | membership4_ | ref |
> >> >>> FKE03761CB7DEF8466,MFRMEMITEM_COMPOSITE_IDX1 |
> >> >>> FKE03761CB7DEF8466 | 9 |
> >> >>> ilearn.topicimpl0_.ID | 3 | Using where
> >> >>> |
> >> >>> | 1 | SIMPLE | permission1_ | ref |
> >> >>> MFRPERMLVL_COMPOSITE_IDX1 |
> >> >>> MFRPERMLVL_COMPOSITE_IDX1 | 152 |
> >> >>> ilearn.membership4_.PERMISSION_LEVEL_NAME | 10167 | Using where
> >> >>> |
> >> >>>
> >> >>>
> +----+-------------+--------------+------+-------------------------------------------------+------------------------------+---------+-------------------------------------------+-------+--------------------------+
> >> >>>
> >> >>> The problem occurs when mysql selects a query plan where tables
> >> >>> membership4_ and permission1_ are not at the end but towards the top
> of the
> >> >>> query plan (this query takes several minutes to run):
> >> >>>
> >> >>>
> +----+-------------+--------------+--------+-------------------------------------------------+---------------------------+---------+-------------------------------------------+-------+-------------+
> >> >>> | id | select_type | table | type |
> >> >>> possible_keys | key
> >> >>> | key_len | ref | rows |
> Extra
> >> >>> |
> >> >>>
> >> >>>
> +----+-------------+--------------+--------+-------------------------------------------------+---------------------------+---------+-------------------------------------------+-------+-------------+
> >> >>> | 1 | SIMPLE | membership4_ | range |
> >> >>> FKE03761CB7DEF8466,MFRMEMITEM_COMPOSITE_IDX1 |
> MFRMEMITEM_COMPOSITE_IDX1
> >> >>> | 767 |NULL | 67305 |
> Using where
> >> >>> |
> >> >>> | 1 | SIMPLE | permission1_ | ref |
> >> >>> MFRPERMLVL_NAME_IDX |
> MFRPERMLVL_NAME_IDX
> >> >>> | 152 | ilearn.membership4_.PERMISSION_LEVEL_NAME | 22004 |
> Using where
> >> >>> |
> >> >>> | 1 | SIMPLE | topicimpl0_ | eq_ref |
> >> >>> PRIMARY,FK863DC0BE74C7E92B | PRIMARY
> >> >>> | 8 | ilearn.membership4_.t_surrogateKey | 1 |
> Using where
> >> >>> |
> >> >>> | 1 | SIMPLE | openforumi2_ | eq_ref |
> >> >>> PRIMARY,FKC17608478B5E2A2F | PRIMARY
> >> >>> | 8 | ilearn.topicimpl0_.of_surrogateKey | 1 |
> Using where
> >> >>> |
> >> >>> | 1 | SIMPLE | areaimpl3_ | eq_ref |
> >> >>> PRIMARY,MFR_AREA_CONTEXT_UUID_UNIQUE,CONTEXT_ID | PRIMARY
> >> >>> | 8 | ilearn.openforumi2_.surrogateKey | 1 |
> Using where
> >> >>> |
> >> >>>
> >> >>>
> +----+-------------+--------------+--------+-------------------------------------------------+---------------------------+---------+-------------------------------------------+-------+-------------+
> >> >>>
> >> >>>
> >> >>> At the moment the only way I've been able to make sure mysql doesn't
> >> >>> select the slow query plan is to use straight_join but it appears
> this is
> >> >>> specific to mysql and therefore not supported by hibernate.
> >> >>>
> >> >>> Do we need a to implement a native query specific for MySQL in this
> case?
> >> >>>
> >> >>> Here is some psuedo code to represent what I am thinking:
> >> >>>
> >> >>> HibernateCallback hcb = new HibernateCallback() {
> >> >>> public Object doInHibernate(Session session) throws
> HibernateException,
> >> >>> SQLException {
> >> >>> if
> >> >>>
> ("mysql".equals(serverConfigurationService.getString(vendor at org.sakaiproject.db.api.SqlService
> ))
> >> >>> Query q =
> >> >>>
> session.createSQLQuery(MYSQL_QUERY_GET_NUM_MOD_TOPICS_WITH_MOD_PERM_BY_PERM_LEVEL_NAME);
> >> >>> else
> >> >>> Query q =
> >> >>>
> session.getNamedQuery(QUERY_GET_NUM_MOD_TOPICS_WITH_MOD_PERM_BY_PERM_LEVEL_NAME);
> >> >>> q.setParameterList("membershipList", membershipList);
> >> >>> q.setParameter("contextId", getContextId(), Hibernate.STRING);
> >> >>> q.setParameter("customTypeUuid",
> typeManager.getCustomLevelType(),
> >> >>> Hibernate.STRING);
> >> >>> return q.uniqueResult();
> >> >>> }
> >> >>> };
> >> >>>
> >> >>> Ideas and thoughts most welcome,
> >> >>> Earle
> >> >>>
> >> >>> _______________________________________________
> >> >>> sakai-dev mailing list
> >> >>> sakai-dev at collab.sakaiproject.org
> >> >>> http://collab.sakaiproject.org/mailman/listinfo/sakai-dev
> >> >>>
> >> >>> TO UNSUBSCRIBE: send email to
> >> >>> sakai-dev-unsubscribe at collab.sakaiproject.org with a subject of
> >> >>> "unsubscribe"
> >> >>
> >> >
> >> >
> >> > _______________________________________________
> >> > sakai-dev mailing list
> >> > sakai-dev at collab.sakaiproject.org
> >> > http://collab.sakaiproject.org/mailman/listinfo/sakai-dev
> >> >
> >> > TO UNSUBSCRIBE: send email to
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> >> > with a subject of "unsubscribe"
> >> >
> >
>
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