[SPARK-17229][SQL] PostgresDialect shouldn't widen float and short types during reads #14796
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Test build #64375 has finished for PR 14796 at commit
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Test build #64376 has finished for PR 14796 at commit
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| case FloatType => Some(JdbcType("FLOAT4", Types.FLOAT)) | ||
| case DoubleType => Some(JdbcType("FLOAT8", Types.DOUBLE)) | ||
| case ShortType => Some(JdbcType("SMALLINT", java.sql.Types.SMALLINT)) | ||
| case t: DecimalType => Some( |
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Hi @JoshRosen, do you mind if I ask a question please (although it is a super minor)? It seems java.sql.Types.SMALLINT and Types.SMALLINT are pointing the same constant. Are there a reason to do this like this?
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Ah, no good reason; just my IDE autocomplete acting up. Lemme fix it.
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Test build #64402 has finished for PR 14796 at commit
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LGTM - merging to master. Thanks! |
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What changes were proposed in this pull request?
When reading float4 and smallint columns from PostgreSQL, Spark's
PostgresDialectwidens these types to Decimal and Integer rather than using the narrower Float and Short types. According to https://www.postgresql.org/docs/7.1/static/datatype.html#DATATYPE-TABLE, Postgres maps thesmallinttype to a signed two-byte integer and thereal/float4types to single precision floating point numbers.This patch fixes this by adding more special-cases to
getCatalystType, similar to what was done for the Derby JDBC dialect. I also fixed a similar problem in the write path which causes Spark to create integer columns in Postgres for what should have been ShortType columns.How was this patch tested?
New test cases in
PostgresIntegrationSuite(which I ran manually because Jenkins can't run it right now).