Hi
I am sending updated version - it allow third optional argument that
specify where searching should to start. With it is possible repeatably
call this function.
Regards
Pavel
2015-01-17 23:43 GMT+01:00 Pavel Stehule <[email protected]>:
> Hi
>
> here is a proof concept of array_offset function
>
> possible question:
>
> * used comparation "=" or "IS NOT DISTINCT FROM"
>
> In this initial proof concept I used "IS NOT DISTINCT FROM" operator - but
> my opinion is not strong in this question. Both has some advantages and
> disadvantages.
>
> Regards
>
> Pavel
>
>
> 2015-01-16 19:12 GMT+01:00 Pavel Stehule <[email protected]>:
>
>>
>>
>> 2015-01-16 18:37 GMT+01:00 Jim Nasby <[email protected]>:
>>
>>> On 1/16/15 11:16 AM, Pavel Stehule wrote:
>>>
>>>>
>>>>
>>>> 2015-01-16 17:57 GMT+01:00 Jim Nasby <[email protected] <mailto:
>>>> [email protected]>>:
>>>>
>>>> On 1/16/15 3:39 AM, Pavel Stehule wrote:
>>>>
>>>> I am proposing a simple function, that returns a position of
>>>> element in array.
>>>>
>>>>
>>>> Yes please!
>>>>
>>>> FUNCTION array_position(anyarray, anyelement) RETURNS int
>>>>
>>>>
>>>> That won't work on a multi-dimensional array. Ideally it needs to
>>>> accept a slice or an element and return the specifier for the slice.
>>>>
>>>>
>>>> It is question, what is a result - probably, there can be a
>>>> multidimensional variant, where result will be a array
>>>>
>>>> array_position([1,2,3],2) --> 2
>>>> array_position([[1,2],[2,3],[3,4]], [2,3]) --> 2 /* 2nd parameter
>>>> should to have N-1 dimension of first parameter */
>>>>
>>>
>>> The problem with that is you can't actually use '2' to get [2,3] back:
>>>
>>> select (array[[1,2,3],[4,5,6],[7,8,9]])[1] IS NULL;
>>> ?column?
>>> ----------
>>> t
>>> (1 row)
>>>
>>
>> yes, but when you are searching a array in array you can use a full slice
>> selection:
>>
>> postgres=# select (ARRAY[[1,2],[4,5]])[1][1:2]; -- [1:2] should be a
>> constant every time in this case -- so it should not be returned
>> array
>> ---------
>> {{1,2}}
>> (1 row)
>>
>>
>>
>>
>>>
>>> I think the bigger problem here is we need something better than slices
>>> for handling subsets of arrays. Even if the function returned [2:2] it's
>>> still going to behave differently than it will in the non-array case
>>> because you won't be getting the expected number of dimensions back. :(
>>>
>>
>> you cannot to return a slice and I don't propose it, although we can
>> return a range type or array of range type - but still we cannot to use
>> range for a arrays.
>>
>>>
>>> array_position_md([1,2,3],2) --> [2]
>>>> array_position_md([[1,2],[2,3],[3,4]], 2) --> [2,1]
>>>>
>>>> another question is how to solve more than one occurrence on one value
>>>> - probably two sets of functions - first returns first occurrence of value,
>>>> second returns set of occurrence
>>>>
>>>
>>> Gee, if only way had some way to return multiple elements of
>>> something... ;P
>>>
>>> In other words, I think all of these should actually return an array of
>>> positions. I think it's OK for someone that only cares about the first
>>> instance to just do [1].
>>
>>
>> there can be two functions - "position" - returns first and "positions"
>> returns all as a array
>>
>>
>>>
>>> --
>>> Jim Nasby, Data Architect, Blue Treble Consulting
>>> Data in Trouble? Get it in Treble! http://BlueTreble.com
>>>
>>
>>
>
diff --git a/doc/src/sgml/array.sgml b/doc/src/sgml/array.sgml
new file mode 100644
index 9ea1068..b3630b4
*** a/doc/src/sgml/array.sgml
--- b/doc/src/sgml/array.sgml
*************** SELECT * FROM sal_emp WHERE pay_by_quart
*** 600,605 ****
--- 600,614 ----
index, as described in <xref linkend="indexes-types">.
</para>
+ <para>
+ You can also search any value in array using the <function>array_offset</>
+ function (It returns a position of first occurrence of value in the array):
+
+ <programlisting>
+ SELECT array_offset(ARRAY['sun','mon','tue','wen','thu','fri','sat'], 'mon');
+ </programlisting>
+ </para>
+
<tip>
<para>
Arrays are not sets; searching for specific array elements
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
new file mode 100644
index 5e7b000..62c9f7f
*** a/doc/src/sgml/func.sgml
--- b/doc/src/sgml/func.sgml
*************** SELECT NULLIF(value, '(none)') ...
*** 11474,11479 ****
--- 11474,11482 ----
<primary>array_lower</primary>
</indexterm>
<indexterm>
+ <primary>array_offset</primary>
+ </indexterm>
+ <indexterm>
<primary>array_prepend</primary>
</indexterm>
<indexterm>
*************** SELECT NULLIF(value, '(none)') ...
*** 11592,11597 ****
--- 11595,11613 ----
</row>
<row>
<entry>
+ <literal>
+ <function>array_offset</function>(<type>anyarray</type>, <type>anyelement</type> <optional>, <type>int</type></optional>)
+ </literal>
+ </entry>
+ <entry><type>int</type></entry>
+ <entry>returns a offset of first occurrence of some element in a array. It uses
+ a <literal>IS NOT DISTINCT FROM</> operator for comparation. Third
+ optional argument can specify a initial offset when searching starts. </entry>
+ <entry><literal>array_offset(ARRAY['sun','mon','tue','wen','thu','fri','sat'], 'mon')</literal></entry>
+ <entry><literal>2</literal></entry>
+ </row>
+ <row>
+ <entry>
<literal>
<function>array_prepend</function>(<type>anyelement</type>, <type>anyarray</type>)
</literal>
diff --git a/src/backend/utils/adt/array_userfuncs.c b/src/backend/utils/adt/array_userfuncs.c
new file mode 100644
index 600646e..2a65806
*** a/src/backend/utils/adt/array_userfuncs.c
--- b/src/backend/utils/adt/array_userfuncs.c
***************
*** 15,20 ****
--- 15,23 ----
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
+ #include "utils/typcache.h"
+
+ static int array_offset_common(FunctionCallInfo fcinfo);
/*-----------------------------------------------------------------------------
*************** array_agg_array_finalfn(PG_FUNCTION_ARGS
*** 612,614 ****
--- 615,759 ----
PG_RETURN_DATUM(result);
}
+
+
+ /*
+ * array_offset - returns a offset of entered element in a array.
+ * Returns NULL when values is not a element of the array. It allow
+ * searching a NULL value due using a NOT DISTINCT FROM operator.
+ *
+ * Biggest difference against width_array is unsorted input array.
+ */
+ Datum
+ array_offset(PG_FUNCTION_ARGS)
+ {
+ PG_RETURN_INT32(array_offset_common(fcinfo));
+ }
+
+
+ Datum
+ array_offset_start(PG_FUNCTION_ARGS)
+ {
+ PG_RETURN_INT32(array_offset_common(fcinfo));
+ }
+
+ /*
+ * Common part for functions array_offset and array_offset_startpos
+ */
+ static int
+ array_offset_common(FunctionCallInfo fcinfo)
+ {
+ ArrayType *array;
+ Oid collation = PG_GET_COLLATION();
+ Oid element_type;
+ Datum searched_element = (Datum) 0,
+ value;
+ bool isnull;
+ int32 offset = 0,
+ offset_min = 1;
+ bool found = false;
+ TypeCacheEntry *typentry;
+ ArrayMetaState *my_extra;
+ bool null_search;
+ ArrayIterator array_iterator;
+
+ if (PG_ARGISNULL(0))
+ PG_RETURN_NULL();
+
+ array = PG_GETARG_ARRAYTYPE_P(0);
+ element_type = ARR_ELEMTYPE(array);
+
+ if (PG_ARGISNULL(1))
+ {
+ if (!array_contains_nulls(array))
+ PG_RETURN_NULL();
+ null_search = true;
+ }
+ else
+ {
+ searched_element = PG_GETARG_DATUM(1);
+ null_search = false;
+ }
+
+ if (PG_NARGS() == 3)
+ {
+ if (PG_ARGISNULL(2))
+ ereport(ERROR,
+ (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+ errmsg("initial offset should not be NULL")));
+
+ offset_min = PG_GETARG_INT32(2);
+ }
+
+ element_type = ARR_ELEMTYPE(array);
+
+ /* cache operator info */
+ my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
+ if (my_extra == NULL)
+ {
+ fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
+ sizeof(ArrayMetaState));
+ my_extra = (ArrayMetaState *) fcinfo->flinfo->fn_extra;
+ my_extra->element_type = ~element_type;
+ }
+
+ if (my_extra->element_type != element_type)
+ {
+ get_typlenbyvalalign(element_type,
+ &my_extra->typlen,
+ &my_extra->typbyval,
+ &my_extra->typalign);
+
+ typentry = lookup_type_cache(element_type,
+ TYPECACHE_EQ_OPR_FINFO);
+
+ if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
+ ereport(ERROR,
+ (errcode(ERRCODE_UNDEFINED_FUNCTION),
+ errmsg("could not identify an equality operator for type %s",
+ format_type_be(element_type))));
+
+ my_extra->element_type = element_type;
+ fmgr_info(typentry->eq_opr_finfo.fn_oid, &my_extra->proc);
+ }
+
+ array_iterator = array_create_iterator(array, 0, my_extra);
+
+ while (array_iterate(array_iterator, &value, &isnull))
+ {
+ offset += 1;
+
+ if (offset < offset_min)
+ continue;
+
+ if (isnull || null_search)
+ {
+
+ if (isnull && null_search)
+ {
+ found = true;
+ break;
+ }
+ else
+ continue;
+ }
+
+ if (DatumGetBool(FunctionCall2Coll(&my_extra->proc, collation,
+ searched_element,
+ value)))
+ {
+ found = true;
+ break;
+ }
+ }
+
+ array_free_iterator(array_iterator);
+
+ /* Avoid leaking memory when handed toasted input */
+ PG_FREE_IF_COPY(array, 0);
+
+ if (!found)
+ PG_RETURN_NULL();
+
+ PG_RETURN_INT32(offset);
+ }
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
new file mode 100644
index 5591b46..9ab1da0
*** a/src/backend/utils/adt/arrayfuncs.c
--- b/src/backend/utils/adt/arrayfuncs.c
*************** arraycontained(PG_FUNCTION_ARGS)
*** 3945,3951 ****
* The passed-in array must remain valid for the lifetime of the iterator.
*/
ArrayIterator
! array_create_iterator(ArrayType *arr, int slice_ndim)
{
ArrayIterator iterator = palloc0(sizeof(ArrayIteratorData));
--- 3945,3951 ----
* The passed-in array must remain valid for the lifetime of the iterator.
*/
ArrayIterator
! array_create_iterator(ArrayType *arr, int slice_ndim, ArrayMetaState *mstate)
{
ArrayIterator iterator = palloc0(sizeof(ArrayIteratorData));
*************** array_create_iterator(ArrayType *arr, in
*** 3962,3971 ****
iterator->arr = arr;
iterator->nullbitmap = ARR_NULLBITMAP(arr);
iterator->nitems = ArrayGetNItems(ARR_NDIM(arr), ARR_DIMS(arr));
! get_typlenbyvalalign(ARR_ELEMTYPE(arr),
! &iterator->typlen,
! &iterator->typbyval,
! &iterator->typalign);
/*
* Remember the slicing parameters.
--- 3962,3981 ----
iterator->arr = arr;
iterator->nullbitmap = ARR_NULLBITMAP(arr);
iterator->nitems = ArrayGetNItems(ARR_NDIM(arr), ARR_DIMS(arr));
!
! if (mstate != NULL)
! {
! Assert(mstate->element_type == ARR_ELEMTYPE(arr));
!
! iterator->typlen = mstate->typlen;
! iterator->typbyval = mstate->typbyval;
! iterator->typalign = mstate->typalign;
! }
! else
! get_typlenbyvalalign(ARR_ELEMTYPE(arr),
! &iterator->typlen,
! &iterator->typbyval,
! &iterator->typalign);
/*
* Remember the slicing parameters.
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
new file mode 100644
index 9edfdb8..b4424e9
*** a/src/include/catalog/pg_proc.h
--- b/src/include/catalog/pg_proc.h
*************** DATA(insert OID = 515 ( array_larger
*** 895,900 ****
--- 895,904 ----
DESCR("larger of two");
DATA(insert OID = 516 ( array_smaller PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 2277 "2277 2277" _null_ _null_ _null_ _null_ array_smaller _null_ _null_ _null_ ));
DESCR("smaller of two");
+ DATA(insert OID = 3277 ( array_offset PGNSP PGUID 12 1 0 0 0 f f f f f f i 2 0 23 "2277 2283" _null_ _null_ _null_ _null_ array_offset _null_ _null_ _null_ ));
+ DESCR("returns a offset of value in array");
+ DATA(insert OID = 3278 ( array_offset PGNSP PGUID 12 1 0 0 0 f f f f f f i 3 0 23 "2277 2283 23" _null_ _null_ _null_ _null_ array_offset_start _null_ _null_ _null_ ));
+ DESCR("returns a offset of value in array with start index");
DATA(insert OID = 1191 ( generate_subscripts PGNSP PGUID 12 1 1000 0 0 f f f f t t i 3 0 23 "2277 23 16" _null_ _null_ _null_ _null_ generate_subscripts _null_ _null_ _null_ ));
DESCR("array subscripts generator");
DATA(insert OID = 1192 ( generate_subscripts PGNSP PGUID 12 1 1000 0 0 f f f f t t i 2 0 23 "2277 23" _null_ _null_ _null_ _null_ generate_subscripts_nodir _null_ _null_ _null_ ));
diff --git a/src/include/utils/array.h b/src/include/utils/array.h
new file mode 100644
index 694bce7..53bea2e
*** a/src/include/utils/array.h
--- b/src/include/utils/array.h
*************** extern ArrayBuildStateAny *accumArrayRes
*** 314,320 ****
extern Datum makeArrayResultAny(ArrayBuildStateAny *astate,
MemoryContext rcontext, bool release);
! extern ArrayIterator array_create_iterator(ArrayType *arr, int slice_ndim);
extern bool array_iterate(ArrayIterator iterator, Datum *value, bool *isnull);
extern void array_free_iterator(ArrayIterator iterator);
--- 314,320 ----
extern Datum makeArrayResultAny(ArrayBuildStateAny *astate,
MemoryContext rcontext, bool release);
! extern ArrayIterator array_create_iterator(ArrayType *arr, int slice_ndim, ArrayMetaState *mstate);
extern bool array_iterate(ArrayIterator iterator, Datum *value, bool *isnull);
extern void array_free_iterator(ArrayIterator iterator);
*************** extern Datum array_agg_finalfn(PG_FUNCTI
*** 348,353 ****
--- 348,356 ----
extern Datum array_agg_array_transfn(PG_FUNCTION_ARGS);
extern Datum array_agg_array_finalfn(PG_FUNCTION_ARGS);
+ extern Datum array_offset(PG_FUNCTION_ARGS);
+ extern Datum array_offset_start(PG_FUNCTION_ARGS);
+
/*
* prototypes for functions defined in array_typanalyze.c
*/
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
new file mode 100644
index ae5421f..3d87520
*** a/src/pl/plpgsql/src/pl_exec.c
--- b/src/pl/plpgsql/src/pl_exec.c
*************** exec_stmt_foreach_a(PLpgSQL_execstate *e
*** 2304,2310 ****
errmsg("FOREACH loop variable must not be of an array type")));
/* Create an iterator to step through the array */
! array_iterator = array_create_iterator(arr, stmt->slice);
/* Identify iterator result type */
if (stmt->slice > 0)
--- 2304,2310 ----
errmsg("FOREACH loop variable must not be of an array type")));
/* Create an iterator to step through the array */
! array_iterator = array_create_iterator(arr, stmt->slice, NULL);
/* Identify iterator result type */
if (stmt->slice > 0)
diff --git a/src/test/regress/expected/arrays.out b/src/test/regress/expected/arrays.out
new file mode 100644
index d33c9b9..c34f61c
*** a/src/test/regress/expected/arrays.out
--- b/src/test/regress/expected/arrays.out
*************** SELECT array_cat(ARRAY[[3,4],[5,6]], ARR
*** 366,371 ****
--- 366,441 ----
{{3,4},{5,6},{1,2}}
(1 row)
+ SELECT array_offset(ARRAY[1,2,3,4,5], 4);
+ array_offset
+ --------------
+ 4
+ (1 row)
+
+ SELECT array_offset(ARRAY[5,3,4,2,1], 4);
+ array_offset
+ --------------
+ 3
+ (1 row)
+
+ SELECT array_offset(ARRAY[[1,2],[3,4]], 3);
+ array_offset
+ --------------
+ 3
+ (1 row)
+
+ SELECT array_offset(ARRAY[[1,2],[3,4]], 4);
+ array_offset
+ --------------
+ 4
+ (1 row)
+
+ SELECT array_offset(ARRAY['sun','mon','tue','wen','thu','fri','sat'], 'mon');
+ array_offset
+ --------------
+ 2
+ (1 row)
+
+ SELECT array_offset(ARRAY['sun','mon','tue','wen','thu','fri','sat'], 'sat');
+ array_offset
+ --------------
+ 7
+ (1 row)
+
+ SELECT array_offset(ARRAY['sun','mon','tue','wen','thu','fri','sat'], NULL);
+ array_offset
+ --------------
+
+ (1 row)
+
+ SELECT array_offset(ARRAY['sun','mon','tue','wen','thu',NULL,'fri','sat'], NULL);
+ array_offset
+ --------------
+ 6
+ (1 row)
+
+ SELECT array_offset(ARRAY['sun','mon','tue','wen','thu',NULL,'fri','sat'], 'sat');
+ array_offset
+ --------------
+ 8
+ (1 row)
+
+ do $$
+ declare
+ o int;
+ a int[] := ARRAY[1,2,3,2,3,1,2];
+ begin
+ o := array_offset(a, 2);
+ while o is not null
+ loop
+ raise notice '%', o;
+ o := array_offset(a, 2, o + 1);
+ end loop;
+ end
+ $$ language plpgsql;
+ NOTICE: 2
+ NOTICE: 4
+ NOTICE: 7
-- operators
SELECT a FROM arrtest WHERE b = ARRAY[[[113,142],[1,147]]];
a
diff --git a/src/test/regress/sql/arrays.sql b/src/test/regress/sql/arrays.sql
new file mode 100644
index 733c19b..68169b2
*** a/src/test/regress/sql/arrays.sql
--- b/src/test/regress/sql/arrays.sql
*************** SELECT array_cat(ARRAY[1,2], ARRAY[3,4])
*** 185,190 ****
--- 185,214 ----
SELECT array_cat(ARRAY[1,2], ARRAY[[3,4],[5,6]]) AS "{{1,2},{3,4},{5,6}}";
SELECT array_cat(ARRAY[[3,4],[5,6]], ARRAY[1,2]) AS "{{3,4},{5,6},{1,2}}";
+ SELECT array_offset(ARRAY[1,2,3,4,5], 4);
+ SELECT array_offset(ARRAY[5,3,4,2,1], 4);
+ SELECT array_offset(ARRAY[[1,2],[3,4]], 3);
+ SELECT array_offset(ARRAY[[1,2],[3,4]], 4);
+ SELECT array_offset(ARRAY['sun','mon','tue','wen','thu','fri','sat'], 'mon');
+ SELECT array_offset(ARRAY['sun','mon','tue','wen','thu','fri','sat'], 'sat');
+ SELECT array_offset(ARRAY['sun','mon','tue','wen','thu','fri','sat'], NULL);
+ SELECT array_offset(ARRAY['sun','mon','tue','wen','thu',NULL,'fri','sat'], NULL);
+ SELECT array_offset(ARRAY['sun','mon','tue','wen','thu',NULL,'fri','sat'], 'sat');
+
+ do $$
+ declare
+ o int;
+ a int[] := ARRAY[1,2,3,2,3,1,2];
+ begin
+ o := array_offset(a, 2);
+ while o is not null
+ loop
+ raise notice '%', o;
+ o := array_offset(a, 2, o + 1);
+ end loop;
+ end
+ $$ language plpgsql;
+
-- operators
SELECT a FROM arrtest WHERE b = ARRAY[[[113,142],[1,147]]];
SELECT NOT ARRAY[1.1,1.2,1.3] = ARRAY[1.1,1.2,1.3] AS "FALSE";
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