AMQ-9541 limit expensive queries on the database side #1275
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| try { | ||
| s = c.getConnection().prepareStatement(this.statements.getFindDurableSubMessagesByPriorityStatement()); | ||
| s = c.getConnection().prepareStatement(this.limitQuery(this.statements.getFindDurableSubMessagesByPriorityStatement())); | ||
| s.setMaxRows(Math.min(maxReturned * 2, maxRows)); |
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I'm not sure why there is "* 2" for the setMaxRows
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Not an expert, but I did some git blame digging, the * 2 got introduced in https://issues.apache.org/jira/browse/AMQ-2980, to take into account the messages from low and high priority queues, to ensure that none get lost and to not hog more memory than needed. Down the road this happened java.sql.SQLException: setMaxRows() out of range. 50871918 > 50000000. (https://issues.apache.org/jira/browse/AMQ-1870). The solution to this was to pick the lowest of two values (maxReturner * 2) and maxRows, to ensure such exception does not happen.
| try { | ||
| s = c.getConnection().prepareStatement(this.statements.getFindDurableSubMessagesStatement()); | ||
| s = c.getConnection().prepareStatement(this.limitQuery(this.statements.getFindDurableSubMessagesStatement())); | ||
| s.setMaxRows(Math.min(maxReturned * 2, maxRows)); |
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I'm not sure why there is "* 2" for the setMaxRows
…ere there is a setMaxRows on the statement.
jeanouii
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@jeanouii i Sorry, not following this logic here. Isn't this.limitQuery a no-ops? It just returns the original query (line 1188) ^ Ah I guess this is the default. It will be over-written in the class that extends it. |
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@jeanouii LGTM. However, this PR should be open against the main branch not a release branch. If you want the fix to only be in a release branch, it can be backported later. |
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@kenliao94 reviving this PR a little bit. I can also backport to 5.19.x as it's still maintained |
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…ere there is a setMaxRows on the statement.