[SERVER-14496] Add limit parameter to $or operator to provide control of the number of queries that will be executed in parallel Created: 08/Jul/14 Updated: 09/Jul/16 Resolved: 14/Jul/14 |
|
| Status: | Closed |
| Project: | Core Server |
| Component/s: | Querying |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Improvement | Priority: | Major - P3 |
| Reporter: | Eoin Brazil | Assignee: | Ramon Fernandez Marina |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
|
||||||||
| Participants: | |||||||||
| Description |
|
Decide whether or not this is necessary and if it is then implement. The current $or operator behaviour executes all clauses of an $or in parallel. The default behaviour should remain unchanged, however is it possible to add a control to limit the number of parallel queries (individual $or clauses executed) launched. With a poorly designed query this can cause performance issues at the mongod level and at a sharded level can trigger timeouts from the mongos processes. |
| Comments |
| Comment by J Rassi [ 14/Jul/14 ] |
|
It is a misconception that parallel processing is used to execute separate branches of $or queries simultaneously. |