Details
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Task
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Status: Closed
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Critical - P2
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Resolution: Fixed
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None
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None
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None
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Fully Compatible
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Execution Team 2021-08-09, Execution Team 2021-08-23, Execution Team 2021-09-06
Description
SERVER-56509 introduced a bug where the unique index constraint was not enforced in some cases. We should add more test coverage for this.
The issue could be reproduced with the following script that we can base additional testing on:
function repro1() {
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db.c.drop()
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db.c.createIndex({t: 1, i: 1}, {unique: true})
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const n = 10000
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const t = 0
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for (var i = 0; i < n; i++)
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db.c.insert({t, i})
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for (iter = 0; ; iter++) {
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print("iter", iter)
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for (var i = 0; i < n; i++) {
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r = db.c.insert({t, i, x: 'x'})
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if (r.nInserted != 0)
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print("dup!", t, i, "iter", iter, "count", db.c.count({t, i}))
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}
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}
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}
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Which reproduces the issue after a couple of iterations:
iter 0
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iter 1
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dup! 0 9999 iter 1 count 2
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A multithreaded version also reproduces:
function repro() {
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db.c.drop()
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db.c.createIndex({t: 1, i: 1}, {unique: true})
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nthreads = 100
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threads = []
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for (var t=0; t<nthreads; t++) {
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thread = new Thread(function(t) {
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for (var i = 0; i < 100; i++)
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db.c.insert({t, i, x: 'x'})
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while (true) {
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for (var i = 0; i < 100; i++) {
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r = db.c.insert({t, i, x: 'x'})
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if (r.nInserted != 0)
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print("dup!", t, i, "count", db.c.count({t, i}))
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}
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}
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}, t)
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threads.push(thread)
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thread.start()
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}
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for (var t = 0; t < nthreads; t++)
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threads[t].join()
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}
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Attachments
Issue Links
- is related to
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- Closed
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SERVER-56509 Wrap unique index insertion _keyExists call in a WT cursor reconfigure.
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- Closed
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