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| -rw-r--r-- | docs/sql-programming-guide.md | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/docs/sql-programming-guide.md b/docs/sql-programming-guide.md index 2aea8a8aed..1b5fde991e 100644 --- a/docs/sql-programming-guide.md +++ b/docs/sql-programming-guide.md @@ -831,13 +831,10 @@ turning on some experimental options. ## Caching Data In Memory -Spark SQL can cache tables using an in-memory columnar format by calling `sqlContext.cacheTable("tableName")`. +Spark SQL can cache tables using an in-memory columnar format by calling `sqlContext.cacheTable("tableName")` or `schemaRDD.cache()`. Then Spark SQL will scan only required columns and will automatically tune compression to minimize memory usage and GC pressure. You can call `sqlContext.uncacheTable("tableName")` to remove the table from memory. -Note that if you call `schemaRDD.cache()` rather than `sqlContext.cacheTable(...)`, tables will _not_ be cached using -the in-memory columnar format, and therefore `sqlContext.cacheTable(...)` is strongly recommended for this use case. - Configuration of in-memory caching can be done using the `setConf` method on SQLContext or by running `SET key=value` commands using SQL. |