[IMPALA-7186] Docs for kudu_read_mode

• Type: Task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 3.1.0
• Fix Version/s: Impala 3.1.0
• Component/s: Docs
• Epic Color: ghx-label-7
• Assignee: Alexandra Rodoni
• Reporter: Thomas Tauber-Marshall
• Created: 19/Jun/18 22:58
• Updated: 29/May/19 15:34
• Resolved: 08/Dec/18 00:52

Description

IMPALA-6812 added a new query option, KUDU_READ_MODE, which should be documented with something like:

KUDU_READ_MODE Query Option

This query option allows users to set a desired consistency level for scans of Kudu tables. Possible values are DEFAULT, READ_LATEST, and READ_AT_SNAPSHOT. If DEFAULT is specified, the value of the startup flag '--kudu_read_mode' will be used.

READ_LATEST
Kudu provides no consistency guarantees for this mode, expect that all returned rows were committed at some point, sometimes known as 'Read Committed' isolation.

READ_AT_SNAPSHOT
Kudu will take a snapshot of the current state of the data and perform the scan over the snapshot, possibly after briefly waiting for ongoing writes to complete. This provides "Read Your Writes" consistency within a single Impala session, except in the case of a Kudu leader change. See the Kudu documentation for more details.

Type: string
Default: DEFAULT
Added in: Impala 3.1

Issue Links

• relates to: IMPALA-6812 Kudu scans not returning all rows