Use DCAwareRoundRobinPolicy as fallback for TokenAwarePolicy #1285
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- Previously, RoundRobinPolicy would attempt cross-dc writes Signed-off-by: Prithvi Raj <p.r@uber.com>
vprithvi
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jpkrohling,
objectiser,
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yurishkuro
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ghost
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black-adder
approved these changes
Jan 16, 2019
| if c.LocalDC != "" { | ||
| fallbackHostSelectionPolicy = gocql.DCAwareRoundRobinPolicy(c.LocalDC) | ||
| } | ||
| cluster.PoolConfig.HostSelectionPolicy = gocql.TokenAwareHostPolicy(fallbackHostSelectionPolicy, gocql.ShuffleReplicas()) |
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what does gocql.ShuffleReplicas() do?
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There can be multiple replicas (equal to RF) for a given token. ShuffleReplicas selects one of these replicas at random instead of deterministically selecting a replica.
yurishkuro
approved these changes
Jan 16, 2019
plugin/storage/cassandra/options.go
Outdated
| flagSet.String( | ||
| nsConfig.namespace+suffixDC, | ||
| nsConfig.LocalDC, | ||
| "The Cassandra local data center for DC Aware host selection") |
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The Cassandra name of local data center...
Signed-off-by: Prithvi Raj <p.r@uber.com>
Codecov Report
@@ Coverage Diff @@
## master #1285 +/- ##
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Coverage ? 100%
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Files ? 161
Lines ? 7198
Branches ? 0
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Hits ? 7198
Misses ? 0
Partials ? 0
Continue to review full report at Codecov.
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Which problem is this PR solving?
Short description of the changes
DCAwareRoundRobinas a fallback forTokenAwareHostPolicy