CountStarDeltaTable Scala Extractor¶

CountStarDeltaTable is an extractor object (Scala) to extractGlobalCount for an Aggregate logical operator.

Matching Aggregate¶

unapply(
  plan: Aggregate): Option[Long]

unapply extractGlobalCount for an Aggregate (Spark SQL) logical operator with the following:

• No grouping expressions
• Alias(AggregateExpression(Count(Seq(Literal(1, _))), Complete, false, None, _), _) aggregate expression
• DeltaTable over a TahoeLogFileIndex with no partition filters

Otherwise, unapply gives None (to indicate no match).

unapply is used when:

• OptimizeMetadataOnlyDeltaQuery is requested to optimizeQueryWithMetadata

extractGlobalCount¶

extractGlobalCount(
  tahoeLogFileIndex: TahoeLogFileIndex): Option[Long]

extractGlobalCount gets a DeltaScanGenerator for the given TahoeLogFileIndex.

extractGlobalCount requests the DeltaScanGenerator to filesWithStatsForScan (that gives a DataFrame) to execute the following aggregations on:

• sum("stats.numRecords")
• count(when(col("stats.numRecords").isNull, 1))