Add table option to skip empty updates #66
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
rkistner
reviewed
Mar 20, 2025
| fn begin_impl(tab: &mut VirtualTable) -> Result<(), SQLiteError> { | ||
| let db = tab.db; | ||
|
|
||
| let insert_statement = db.prepare_v3("INSERT INTO ps_crud(tx_id, data) VALUES (?1, ?2)", 0)?; | ||
| const SQL: &str = formatcp!("\ | ||
| WITH insertion (tx_id, data) AS (VALUES (?1, ?2)) |
There was a problem hiding this comment.
To check if there is data in the patch, it might be more efficient to just check data->'data' != '{}' - json_each could potentially add some overhead here. I haven't done any actual benchmarks though - the overhead may be negligible.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
For updates on views that happen to not change any columns (e.g. a
SET col = LOWER(col)where all values incolwere already in lower case), we currently insert an empty update operation into the local upload queue. While this can be resolved by users rewriting SQL statements and typically shouldn't make up a bulk of the queue, we've seen a report claiming that skipping empty updates speeds up uploads: powersync-ja/powersync-kotlin#144.Ignoring empty updates entirely might break users relying on the current behavior, so this adds an opt-in option to ignore schema updates. For this, the
powersync_crud_vtab gains a new hidden column with option flags that can be set for inserts.FLAG_INCLUDE_EMPTY_UPDATE, which is enabled by default, preserves the current behavior. Clearing that flag, which the generated views do when theignore_empty_updateoption is set on the JSON schema description for a table, willl make the vtab ignore empty updates.