feat: Doc fetch from cursor to be non-blocking and blocking
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hzxa21
approved these changes
Nov 11, 2024
delivery/subscription.mdx
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| @@ -83,33 +83,39 @@ If you specify `FULL` instead of the `since_clause`, the subscription cursor sta | |||
| FETCH from cursor function is currently only supported in the PSQL simple query mode. If you are using components like JDBC that default to the extended query mode, please manually set the mode to simple query mode. | |||
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Extended mode is also supported in risingwavelabs/risingwave#17821 starting from v2.0
delivery/subscription.mdx
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| (1 row) | ||
| ``` | ||
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| The `op` column in the result stands for the change operations. It has four options: `insert`, `update_insert`, `delete`, and `update_delete`. For a single UPDATE statement, the subscription log will contain two separate rows: one with `update_insert` and another with `update_delete`. This is because RisingWave treats an UPDATE as a delete of the old value followed by an insert of the new value. As for `rw_timestamp`, it corresponds to the Unix timestamp in milliseconds when the data was written. | ||
| In the example above, the `op` column in the result indicates the type of change operations. There are four options: `insert`, `update_insert`, `delete`, and `update_delete`. For a single UPDATE statement, the subscription log will contain two separate rows: one with `update_insert` and another with `update_delete`. This is because RisingWave treats an UPDATE as a delete of the old value followed by an insert of the new value. As for `rw_timestamp`, it corresponds to the Unix timestamp in milliseconds when the data was written. |
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The four options are in camelCase instead of snake_case: Insert, Delete, UpdateInsert, UpdateDelete.
delivery/subscription.mdx
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| Note that each time `FETCH NEXT FROM cursor_name` is called, it will return one row of incremental data from the subscribed table. It does not return all the incremental data at once, but requires the user to repeatedly call this statement to fetch the data. | ||
| ```sql | ||
| FETCH NEXT/n FROM cursor_name WITH (timeout = 'xx'); |
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Let's give a concrete example for timeout: replace timeout = 'xx' to timeout = '1s'
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Description
Doc
fetch from cursorto be non-blocking and blockingRelated code PR
risingwavelabs/risingwave#18675
Related doc issue
Resolve risingwavelabs/risingwave-docs#2672