From 6819514fca22f8554edcab6e4d0402b0221f03bb Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 4 Feb 2016 23:03:10 -0500 Subject: [PATCH] Add num_nulls() and num_nonnulls() to count NULL arguments. An example use-case is "CHECK(num_nonnulls(a,b,c) = 1)" to assert that exactly one of a,b,c isn't NULL. The functions are variadic, so they can also be pressed into service to count the number of null or nonnull elements in an array. Marko Tiikkaja, reviewed by Pavel Stehule --- doc/src/sgml/func.sgml | 53 +++++++- src/backend/utils/adt/misc.c | 121 +++++++++++++++++ src/include/catalog/catversion.h | 2 +- src/include/catalog/pg_proc.h | 6 + src/include/utils/builtins.h | 4 +- src/test/regress/expected/misc_functions.out | 135 +++++++++++++++++++ src/test/regress/parallel_schedule | 2 +- src/test/regress/serial_schedule | 1 + src/test/regress/sql/misc_functions.sql | 31 +++++ 9 files changed, 347 insertions(+), 8 deletions(-) create mode 100644 src/test/regress/expected/misc_functions.out create mode 100644 src/test/regress/sql/misc_functions.sql diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 139aa2b811..f9eea76fd5 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -182,7 +182,7 @@ - Comparison Operators + Comparison Functions and Operators comparison @@ -190,11 +190,11 @@ - The usual comparison operators are available, shown in . + The usual comparison operators are available, as shown in . - +
Comparison Operators @@ -437,6 +437,49 @@ --> + + Some comparison-related functions are also available, as shown in . + + +
+ Comparison Functions + + + + Function + Description + Example + Example Result + + + + + + + num_nonnulls + + num_nonnulls(VARIADIC "any") + + returns the number of non-NULL arguments + num_nonnulls(1, NULL, 2) + 2 + + + + + num_nulls + + num_nulls(VARIADIC "any") + + returns the number of NULL arguments + num_nulls(1, NULL, 2) + 1 + + + +
+ @@ -10389,7 +10432,7 @@ table2-mapping The standard comparison operators shown in are available for + linkend="functions-comparison-op-table"> are available for jsonb, but not for json. They follow the ordering rules for B-tree operations outlined at . diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c index 6a306f39a9..43f36db47b 100644 --- a/src/backend/utils/adt/misc.c +++ b/src/backend/utils/adt/misc.c @@ -44,6 +44,127 @@ #define atooid(x) ((Oid) strtoul((x), NULL, 10)) +/* + * Common subroutine for num_nulls() and num_nonnulls(). + * Returns TRUE if successful, FALSE if function should return NULL. + * If successful, total argument count and number of nulls are + * returned into *nargs and *nulls. + */ +static bool +count_nulls(FunctionCallInfo fcinfo, + int32 *nargs, int32 *nulls) +{ + int32 count = 0; + int i; + + /* Did we get a VARIADIC array argument, or separate arguments? */ + if (get_fn_expr_variadic(fcinfo->flinfo)) + { + ArrayType *arr; + int ndims, + nitems, + *dims; + bits8 *bitmap; + + Assert(PG_NARGS() == 1); + + /* + * If we get a null as VARIADIC array argument, we can't say anything + * useful about the number of elements, so return NULL. This behavior + * is consistent with other variadic functions - see concat_internal. + */ + if (PG_ARGISNULL(0)) + return false; + + /* + * Non-null argument had better be an array. We assume that any call + * context that could let get_fn_expr_variadic return true will have + * checked that a VARIADIC-labeled parameter actually is an array. So + * it should be okay to just Assert that it's an array rather than + * doing a full-fledged error check. + */ + Assert(OidIsValid(get_base_element_type(get_fn_expr_argtype(fcinfo->flinfo, 0)))); + + /* OK, safe to fetch the array value */ + arr = PG_GETARG_ARRAYTYPE_P(0); + + /* Count the array elements */ + ndims = ARR_NDIM(arr); + dims = ARR_DIMS(arr); + nitems = ArrayGetNItems(ndims, dims); + + /* Count those that are NULL */ + bitmap = ARR_NULLBITMAP(arr); + if (bitmap) + { + int bitmask = 1; + + for (i = 0; i < nitems; i++) + { + if ((*bitmap & bitmask) == 0) + count++; + + bitmask <<= 1; + if (bitmask == 0x100) + { + bitmap++; + bitmask = 1; + } + } + } + + *nargs = nitems; + *nulls = count; + } + else + { + /* Separate arguments, so just count 'em */ + for (i = 0; i < PG_NARGS(); i++) + { + if (PG_ARGISNULL(i)) + count++; + } + + *nargs = PG_NARGS(); + *nulls = count; + } + + return true; +} + +/* + * num_nulls() + * Count the number of NULL arguments + */ +Datum +pg_num_nulls(PG_FUNCTION_ARGS) +{ + int32 nargs, + nulls; + + if (!count_nulls(fcinfo, &nargs, &nulls)) + PG_RETURN_NULL(); + + PG_RETURN_INT32(nulls); +} + +/* + * num_nonnulls() + * Count the number of non-NULL arguments + */ +Datum +pg_num_nonnulls(PG_FUNCTION_ARGS) +{ + int32 nargs, + nulls; + + if (!count_nulls(fcinfo, &nargs, &nulls)) + PG_RETURN_NULL(); + + PG_RETURN_INT32(nargs - nulls); +} + + /* * current_database() * Expose the current database to the user diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h index 568c98f94e..90992f269e 100644 --- a/src/include/catalog/catversion.h +++ b/src/include/catalog/catversion.h @@ -53,6 +53,6 @@ */ /* yyyymmddN */ -#define CATALOG_VERSION_NO 201602031 +#define CATALOG_VERSION_NO 201602041 #endif diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h index 5ded13e2b0..c6b4916f24 100644 --- a/src/include/catalog/pg_proc.h +++ b/src/include/catalog/pg_proc.h @@ -686,6 +686,12 @@ DATA(insert OID = 422 ( hashinet PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 DESCR("hash"); DATA(insert OID = 432 ( hash_numeric PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 23 "1700" _null_ _null_ _null_ _null_ _null_ hash_numeric _null_ _null_ _null_ )); DESCR("hash"); + +DATA(insert OID = 438 ( num_nulls PGNSP PGUID 12 1 0 2276 0 f f f f f f i s 1 0 23 "2276" "{2276}" "{v}" _null_ _null_ _null_ pg_num_nulls _null_ _null_ _null_ )); +DESCR("count the number of NULL arguments"); +DATA(insert OID = 440 ( num_nonnulls PGNSP PGUID 12 1 0 2276 0 f f f f f f i s 1 0 23 "2276" "{2276}" "{v}" _null_ _null_ _null_ pg_num_nonnulls _null_ _null_ _null_ )); +DESCR("count the number of non-NULL arguments"); + DATA(insert OID = 458 ( text_larger PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 25 "25 25" _null_ _null_ _null_ _null_ _null_ text_larger _null_ _null_ _null_ )); DESCR("larger of two"); DATA(insert OID = 459 ( text_smaller PGNSP PGUID 12 1 0 0 0 f f f f t f i s 2 0 25 "25 25" _null_ _null_ _null_ _null_ _null_ text_smaller _null_ _null_ _null_ )); diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h index 5e8e8329b8..c9be32e33a 100644 --- a/src/include/utils/builtins.h +++ b/src/include/utils/builtins.h @@ -490,6 +490,8 @@ extern Datum pg_ls_dir(PG_FUNCTION_ARGS); extern Datum pg_ls_dir_1arg(PG_FUNCTION_ARGS); /* misc.c */ +extern Datum pg_num_nulls(PG_FUNCTION_ARGS); +extern Datum pg_num_nonnulls(PG_FUNCTION_ARGS); extern Datum current_database(PG_FUNCTION_ARGS); extern Datum current_query(PG_FUNCTION_ARGS); extern Datum pg_cancel_backend(PG_FUNCTION_ARGS); @@ -823,7 +825,7 @@ extern Datum textoverlay_no_len(PG_FUNCTION_ARGS); extern Datum name_text(PG_FUNCTION_ARGS); extern Datum text_name(PG_FUNCTION_ARGS); extern int varstr_cmp(char *arg1, int len1, char *arg2, int len2, Oid collid); -extern void varstr_sortsupport(SortSupport ssup, Oid collid, bool bpchar); +extern void varstr_sortsupport(SortSupport ssup, Oid collid, bool bpchar); extern int varstr_levenshtein(const char *source, int slen, const char *target, int tlen, int ins_c, int del_c, int sub_c, diff --git a/src/test/regress/expected/misc_functions.out b/src/test/regress/expected/misc_functions.out new file mode 100644 index 0000000000..130a0e4be3 --- /dev/null +++ b/src/test/regress/expected/misc_functions.out @@ -0,0 +1,135 @@ +-- +-- num_nulls() +-- +SELECT num_nonnulls(NULL); + num_nonnulls +-------------- + 0 +(1 row) + +SELECT num_nonnulls('1'); + num_nonnulls +-------------- + 1 +(1 row) + +SELECT num_nonnulls(NULL::text); + num_nonnulls +-------------- + 0 +(1 row) + +SELECT num_nonnulls(NULL::text, NULL::int); + num_nonnulls +-------------- + 0 +(1 row) + +SELECT num_nonnulls(1, 2, NULL::text, NULL::point, '', int8 '9', 1.0 / NULL); + num_nonnulls +-------------- + 4 +(1 row) + +SELECT num_nonnulls(VARIADIC '{1,2,NULL,3}'::int[]); + num_nonnulls +-------------- + 3 +(1 row) + +SELECT num_nonnulls(VARIADIC '{"1","2","3","4"}'::text[]); + num_nonnulls +-------------- + 4 +(1 row) + +SELECT num_nonnulls(VARIADIC ARRAY(SELECT CASE WHEN i <> 40 THEN i END FROM generate_series(1, 100) i)); + num_nonnulls +-------------- + 99 +(1 row) + +SELECT num_nulls(NULL); + num_nulls +----------- + 1 +(1 row) + +SELECT num_nulls('1'); + num_nulls +----------- + 0 +(1 row) + +SELECT num_nulls(NULL::text); + num_nulls +----------- + 1 +(1 row) + +SELECT num_nulls(NULL::text, NULL::int); + num_nulls +----------- + 2 +(1 row) + +SELECT num_nulls(1, 2, NULL::text, NULL::point, '', int8 '9', 1.0 / NULL); + num_nulls +----------- + 3 +(1 row) + +SELECT num_nulls(VARIADIC '{1,2,NULL,3}'::int[]); + num_nulls +----------- + 1 +(1 row) + +SELECT num_nulls(VARIADIC '{"1","2","3","4"}'::text[]); + num_nulls +----------- + 0 +(1 row) + +SELECT num_nulls(VARIADIC ARRAY(SELECT CASE WHEN i <> 40 THEN i END FROM generate_series(1, 100) i)); + num_nulls +----------- + 1 +(1 row) + +-- special cases +SELECT num_nonnulls(VARIADIC NULL::text[]); + num_nonnulls +-------------- + +(1 row) + +SELECT num_nonnulls(VARIADIC '{}'::int[]); + num_nonnulls +-------------- + 0 +(1 row) + +SELECT num_nulls(VARIADIC NULL::text[]); + num_nulls +----------- + +(1 row) + +SELECT num_nulls(VARIADIC '{}'::int[]); + num_nulls +----------- + 0 +(1 row) + +-- should fail, one or more arguments is required +SELECT num_nonnulls(); +ERROR: function num_nonnulls() does not exist +LINE 1: SELECT num_nonnulls(); + ^ +HINT: No function matches the given name and argument types. You might need to add explicit type casts. +SELECT num_nulls(); +ERROR: function num_nulls() does not exist +LINE 1: SELECT num_nulls(); + ^ +HINT: No function matches the given name and argument types. You might need to add explicit type casts. diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule index b1bc7c716a..bec03165a7 100644 --- a/src/test/regress/parallel_schedule +++ b/src/test/regress/parallel_schedule @@ -89,7 +89,7 @@ test: brin gin gist spgist privileges security_label collate matview lock replic # ---------- # Another group of parallel tests # ---------- -test: alter_generic alter_operator misc psql async dbsize +test: alter_generic alter_operator misc psql async dbsize misc_functions # rules cannot run concurrently with any test that creates a view test: rules diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule index ade9ef1553..7e9b319b0f 100644 --- a/src/test/regress/serial_schedule +++ b/src/test/regress/serial_schedule @@ -119,6 +119,7 @@ test: misc test: psql test: async test: dbsize +test: misc_functions test: rules test: select_views test: portals_p2 diff --git a/src/test/regress/sql/misc_functions.sql b/src/test/regress/sql/misc_functions.sql new file mode 100644 index 0000000000..1a20c1f765 --- /dev/null +++ b/src/test/regress/sql/misc_functions.sql @@ -0,0 +1,31 @@ +-- +-- num_nulls() +-- + +SELECT num_nonnulls(NULL); +SELECT num_nonnulls('1'); +SELECT num_nonnulls(NULL::text); +SELECT num_nonnulls(NULL::text, NULL::int); +SELECT num_nonnulls(1, 2, NULL::text, NULL::point, '', int8 '9', 1.0 / NULL); +SELECT num_nonnulls(VARIADIC '{1,2,NULL,3}'::int[]); +SELECT num_nonnulls(VARIADIC '{"1","2","3","4"}'::text[]); +SELECT num_nonnulls(VARIADIC ARRAY(SELECT CASE WHEN i <> 40 THEN i END FROM generate_series(1, 100) i)); + +SELECT num_nulls(NULL); +SELECT num_nulls('1'); +SELECT num_nulls(NULL::text); +SELECT num_nulls(NULL::text, NULL::int); +SELECT num_nulls(1, 2, NULL::text, NULL::point, '', int8 '9', 1.0 / NULL); +SELECT num_nulls(VARIADIC '{1,2,NULL,3}'::int[]); +SELECT num_nulls(VARIADIC '{"1","2","3","4"}'::text[]); +SELECT num_nulls(VARIADIC ARRAY(SELECT CASE WHEN i <> 40 THEN i END FROM generate_series(1, 100) i)); + +-- special cases +SELECT num_nonnulls(VARIADIC NULL::text[]); +SELECT num_nonnulls(VARIADIC '{}'::int[]); +SELECT num_nulls(VARIADIC NULL::text[]); +SELECT num_nulls(VARIADIC '{}'::int[]); + +-- should fail, one or more arguments is required +SELECT num_nonnulls(); +SELECT num_nulls();