Major Description
Sometimes, we have generated codes they are equal except for comments.
One example is here.
val df = sc.parallelize(1 to 10).toDF df.selectExpr("value + 1").show // query1 df.selectExpr("value + 2").show // query2
The following code is one of generated code when query1 above is executed.
/* 001 */ /* 002 */ public java.lang.Object generate(Object[] references) { /* 003 */ return new SpecificSafeProjection(references); /* 004 */ } /* 005 */ /* 006 */ class SpecificSafeProjection extends org.apache.spark.sql.catalyst.expressions.codegen.BaseProjection { /* 007 */ /* 008 */ private Object[] references; /* 009 */ private MutableRow mutableRow; /* 010 */ private Object[] values; /* 011 */ private org.apache.spark.sql.types.StructType schema; /* 012 */ /* 013 */ /* 014 */ public SpecificSafeProjection(Object[] references) { /* 015 */ this.references = references; /* 016 */ mutableRow = (MutableRow) references[references.length - 1]; /* 017 */ /* 018 */ this.schema = (org.apache.spark.sql.types.StructType) references[0]; /* 019 */ } /* 020 */ /* 021 */ public java.lang.Object apply(java.lang.Object _i) { /* 022 */ InternalRow i = (InternalRow) _i; /* 023 */ /* createexternalrow(if (isnull(input[0, int])) null else input[0, int], StructField((value + 1),IntegerType,false)) */ /* 024 */ values = new Object[1]; /* 025 */ /* if (isnull(input[0, int])) null else input[0, int] */ /* 026 */ /* isnull(input[0, int]) */ /* 027 */ /* input[0, int] */ /* 028 */ int value3 = i.getInt(0); /* 029 */ boolean isNull1 = false; /* 030 */ int value1 = -1; /* 031 */ if (!false && false) { /* 032 */ /* null */ /* 033 */ final int value4 = -1; /* 034 */ isNull1 = true; /* 035 */ value1 = value4; /* 036 */ } else { /* 037 */ /* input[0, int] */ /* 038 */ int value5 = i.getInt(0); /* 039 */ isNull1 = false; /* 040 */ value1 = value5; /* 041 */ } /* 042 */ if (isNull1) { /* 043 */ values[0] = null; /* 044 */ } else { /* 045 */ values[0] = value1; /* 046 */ } /* 047 */ /* 048 */ final org.apache.spark.sql.Row value = new org.apache.spark.sql.catalyst.expressions.GenericRowWithSchema(values, this.schema); /* 049 */ if (false) { /* 050 */ mutableRow.setNullAt(0); /* 051 */ } else { /* 052 */ /* 053 */ mutableRow.update(0, value); /* 054 */ } /* 055 */ /* 056 */ return mutableRow; /* 057 */ } /* 058 */ } /* 059 */
On the other hand, the following code is for query2.
/* 001 */ /* 002 */ public java.lang.Object generate(Object[] references) { /* 003 */ return new SpecificSafeProjection(references); /* 004 */ } /* 005 */ /* 006 */ class SpecificSafeProjection extends org.apache.spark.sql.catalyst.expressions.codegen.BaseProjection { /* 007 */ /* 008 */ private Object[] references; /* 009 */ private MutableRow mutableRow; /* 010 */ private Object[] values; /* 011 */ private org.apache.spark.sql.types.StructType schema; /* 012 */ /* 013 */ /* 014 */ public SpecificSafeProjection(Object[] references) { /* 015 */ this.references = references; /* 016 */ mutableRow = (MutableRow) references[references.length - 1]; /* 017 */ /* 018 */ this.schema = (org.apache.spark.sql.types.StructType) references[0]; /* 019 */ } /* 020 */ /* 021 */ public java.lang.Object apply(java.lang.Object _i) { /* 022 */ InternalRow i = (InternalRow) _i; /* 023 */ /* createexternalrow(if (isnull(input[0, int])) null else input[0, int], StructField((value + 2),IntegerType,false)) */ /* 024 */ values = new Object[1]; /* 025 */ /* if (isnull(input[0, int])) null else input[0, int] */ /* 026 */ /* isnull(input[0, int]) */ /* 027 */ /* input[0, int] */ /* 028 */ int value3 = i.getInt(0); /* 029 */ boolean isNull1 = false; /* 030 */ int value1 = -1; /* 031 */ if (!false && false) { /* 032 */ /* null */ /* 033 */ final int value4 = -1; /* 034 */ isNull1 = true; /* 035 */ value1 = value4; /* 036 */ } else { /* 037 */ /* input[0, int] */ /* 038 */ int value5 = i.getInt(0); /* 039 */ isNull1 = false; /* 040 */ value1 = value5; /* 041 */ } /* 042 */ if (isNull1) { /* 043 */ values[0] = null; /* 044 */ } else { /* 045 */ values[0] = value1; /* 046 */ } /* 047 */ /* 048 */ final org.apache.spark.sql.Row value = new org.apache.spark.sql.catalyst.expressions.GenericRowWithSchema(values, this.schema); /* 049 */ if (false) { /* 050 */ mutableRow.setNullAt(0); /* 051 */ } else { /* 052 */ /* 053 */ mutableRow.update(0, value); /* 054 */ } /* 055 */ /* 056 */ return mutableRow; /* 057 */ } /* 058 */ } /* 059 */
As you can notice, those two generated codes are essentially equal but not equal as String objects so they will be compiled each.
