Craig George created MAILBOX-186:
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Summary: Missing indices on JPA mailstore database results in poor
mailbox listing as the number of messages grows
Key: MAILBOX-186
URL: https://issues.apache.org/jira/browse/MAILBOX-186
Project: James Mailbox
Issue Type: Bug
Components: jpa
Affects Versions: 0.4
Reporter: Craig George
We have an application which queries the IMAP store of Apache James 3 in the
following manner:
{code}
final Message[] messages = this.folder.getMessages();
final FetchProfile fetchProfile = new FetchProfile();
fetchProfile.add(Item.ENVELOPE);
fetchProfile.add(Item.FLAGS);
fetchProfile.add(Item.CONTENT_INFO);
fetchProfile.add(IMAPFolder.FetchProfileItem.HEADERS);
fetchProfile.add(IMAPFolder.FetchProfileItem.SIZE);
fetchProfile.add(UIDFolder.FetchProfileItem.UID);
this.folder.fetch(messages, fetchProfile);
{code}
When this query is performed on a folder with a large number of messages the
response times degrade very quickly. This is due to the following query being
run *for each* message:
{code:sql}
SELECT t0.PROPERTY_ID,
t0.PROPERTY_LINE_NUMBER,
t0.PROPERTY_LOCAL_NAME,
t0.PROPERTY_NAME_SPACE,
t0.PROPERTY_VALUE
FROM MA_DIRECT_APACHE_JAMES.JAMES_MAIL_PROPERTY t0
WHERE t0.MAILBOX_ID = :1
AND t0.MAIL_UID = :2
ORDER BY t0.PROPERTY_LINE_NUMBER ASC
{code}
The problem is that in the {{JAMES_MAIL_PROPERTY}} table only the
{{PROPERTY_LINE_ID}} column is indexed, implicity by virtue of the fact that it
is the primary key. The workaround is to add the following indexes on the table:
{code:sql}
CREATE INDEX I_JMS_MIL_PROPERTY_MSG_ID ON JAMES_MAIL_PROPERTY (MAILBOX_ID,
MAIL_UID);
CREATE INDEX I_JMS_MIL_PROPERTY_LINE_NUMBER ON JAMES_MAIL_PROPERTY
(PROPERTY_LINE_NUMBER);
{code}
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