feat(spanner): support multiplexed session for Partitioned operations #3231
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…o partitioned-query
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Warning: This pull request is touching the following templated files:
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| SessionImpl session = sessionClient.createSession(); | ||
| SessionImpl session; | ||
| if (isMultiplexedSessionEnabled) { | ||
| session = sessionClient.createMultiplexedSession(); |
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Would it not make more sense to use the multiplexed session that we have already created for the normal client? Or otherwise at least just create one multiplexed session that is re-used for all batch read-only transactions? The reason that the current implementation creates a separate session for each transaction is that:
- We don't want to use a session from the pool, because the session might be checked out for a very long time.
- Regular sessions cannot be used for multiple concurrent transactions (although this restriction in reality has been lifted).
| } | ||
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| /** Returns a {@link SessionImpl} that references the existing session with the given name. */ | ||
| SessionImpl sessionWithId(String name, boolean isMultiplexedSession) { |
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We should not add a boolean that indicates whether the session is a multiplexed session or not here, as the caller does not know. The session might have been created by a different client, and this client does not know whether the other client created a regular or a multiplexed session.
| sessionClient.sessionWithId(checkNotNull(batchTransactionId).getSessionId()); | ||
| sessionClient.sessionWithId( | ||
| checkNotNull(batchTransactionId).getSessionId(), | ||
| batchTransactionId.isMultiplexedSession()); |
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We should not pass in multiplexed true/false here, because this client does not know anything about this session. The session might have been created by a different client and shared out-of-band with this client. The fact that this client uses multiplexed sessions does not mean that the other client uses multiplexed sessions (and vice-versa).
| @@ -32,12 +32,18 @@ public class BatchTransactionId implements Serializable { | |||
| private final ByteString transactionId; | |||
| private final String sessionId; | |||
| private final Timestamp timestamp; | |||
| private final boolean isMultiplexedSession; | |||
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Do we need this flag for anything? Otherwise, I think we should remove it. See also my comment above; If a client receives a session ID from another client, then this client does not know whether that session ID is for a regular or a multiplexed session. If such an ID is then used to create a BatchTransactionId, then this could lead to a BatchTransactionId that contains 'false' information.
google-cloud-spanner/src/main/java/com/google/cloud/spanner/DatabaseClientImpl.java
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...oud-spanner/src/main/java/com/google/cloud/spanner/DelayedMultiplexedSessionTransaction.java
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...oud-spanner/src/main/java/com/google/cloud/spanner/DelayedMultiplexedSessionTransaction.java
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...e-cloud-spanner/src/main/java/com/google/cloud/spanner/MultiplexedSessionDatabaseClient.java
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google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionClient.java
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Co-authored-by: Knut Olav Løite <[email protected]>
Co-authored-by: Knut Olav Løite <[email protected]>
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With multiplexed sessions, the client optimises and runs multiple applicable requests concurrently on a single session. A single multiplexed session is sufficient to handle all concurrent partitioned read, query and dml operations.
This can be enabled through an environment variable
GOOGLE_CLOUD_SPANNER_MULTIPLEXED_SESSIONS_PARTITIONED_OPS.