Ran Haim created SPARK-22481:
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Summary: CatalogImpl.refreshTable is slow
Key: SPARK-22481
URL: https://issues.apache.org/jira/browse/SPARK-22481
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 2.2.0, 2.1.2, 2.1.1
Reporter: Ran Haim
Priority: Critical
CatalogImpl.refreshTable was updated in 2.1.1 and since than it has become
really slow.
The cause of the issue is that it is now *always* create a dataset, and this is
redundent most of the time, we only need the dataset if the table is cached.
code before the change:
override def refreshTable(tableName: String): Unit = {
val tableIdent =
sparkSession.sessionState.sqlParser.parseTableIdentifier(tableName)
// Temp tables: refresh (or invalidate) any metadata/data cached in the
plan recursively.
// Non-temp tables: refresh the metadata cache.
sessionCatalog.refreshTable(tableIdent)
// If this table is cached as an InMemoryRelation, drop the original
// cached version and make the new version cached lazily.
val logicalPlan =
sparkSession.sessionState.catalog.lookupRelation(tableIdent)
// Use lookupCachedData directly since RefreshTable also takes databaseName.
val isCached =
sparkSession.sharedState.cacheManager.lookupCachedData(logicalPlan).nonEmpty
if (isCached) {
// Create a data frame to represent the table.
// TODO: Use uncacheTable once it supports database name.
* val df = Dataset.ofRows(sparkSession, logicalPlan)*
// Uncache the logicalPlan.
sparkSession.sharedState.cacheManager.uncacheQuery(df, blocking = true)
// Cache it again.
sparkSession.sharedState.cacheManager.cacheQuery(df,
Some(tableIdent.table))
}
}
after the change:
/override def refreshTable(tableName: String): Unit = {
val tableIdent =
sparkSession.sessionState.sqlParser.parseTableIdentifier(tableName)
// Temp tables: refresh (or invalidate) any metadata/data cached in the
plan recursively.
// Non-temp tables: refresh the metadata cache.
sessionCatalog.refreshTable(tableIdent)
// If this table is cached as an InMemoryRelation, drop the original
// cached version and make the new version cached lazily.
* val table = sparkSession.table(tableIdent)*
if (isCached(table)) {
// Uncache the logicalPlan.
sparkSession.sharedState.cacheManager.uncacheQuery(table, blocking = true)
// Cache it again.
sparkSession.sharedState.cacheManager.cacheQuery(table,
Some(tableIdent.table))
}
}
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