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Add string_to_table() function. 

This splits a string at occurrences of a delimiter.  It is exactly like
string_to_array() except for producing a set of values instead of an
array of values.  Thus, the relationship of these two functions is
the same as between regexp_split_to_table() and regexp_split_to_array().

Although the same results could be had from unnest(string_to_array()),
this is somewhat faster than that, and anyway it seems reasonable to
have it for symmetry with the regexp functions.

Pavel Stehule, reviewed by Peter Smith

Discussion: https://postgr.es/m/CAFj8pRD8HOpjq2TqeTBhSo_QkzjLOhXzGCpKJ4nCs7Y9SQkuPw@mail.gmail.com
This commit is contained in:
Tom Lane 2020-09-02 18:23:56 -04:00
parent fd5e3b2914
commit 66f1630680
6 changed files with 354 additions and 93 deletions
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90
doc/src/sgml/func.sgml
View File

@ -3220,7 +3220,7 @@ repeat('Pg', 4) <returnvalue>PgPgPgPg</returnvalue>
</para>
<para>
Splits <parameter>string</parameter> using a POSIX regular
expression as the delimiter; see
expression as the delimiter, producing an array of results; see
<xref linkend="functions-posix-regexp"/>.
</para>
<para>
@ -3239,7 +3239,7 @@ repeat('Pg', 4) <returnvalue>PgPgPgPg</returnvalue>
</para>
<para>
Splits <parameter>string</parameter> using a POSIX regular
expression as the delimiter; see
expression as the delimiter, producing a set of results; see
<xref linkend="functions-posix-regexp"/>.
</para>
<para>
@ -3460,6 +3460,65 @@ repeat('Pg', 4) <returnvalue>PgPgPgPg</returnvalue>
</para></entry>
</row>
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
<primary>string_to_array</primary>
</indexterm>
<function>string_to_array</function> ( <parameter>string</parameter> <type>text</type>, <parameter>delimiter</parameter> <type>text</type> <optional>, <parameter>null_string</parameter> <type>text</type> </optional> )
<returnvalue>text[]</returnvalue>
</para>
<para>
Splits the <parameter>string</parameter> at occurrences
of <parameter>delimiter</parameter> and forms the resulting fields
into a <type>text</type> array.
If <parameter>delimiter</parameter> is <literal>NULL</literal>,
each character in the <parameter>string</parameter> will become a
separate element in the array.
If <parameter>delimiter</parameter> is an empty string, then
the <parameter>string</parameter> is treated as a single field.
If <parameter>null_string</parameter> is supplied and is
not <literal>NULL</literal>, fields matching that string are
replaced by <literal>NULL</literal>.
</para>
<para>
<literal>string_to_array('xx~~yy~~zz', '~~', 'yy')</literal>
<returnvalue>{xx,NULL,zz}</returnvalue>
</para></entry>
</row>
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
<primary>string_to_table</primary>
</indexterm>
<function>string_to_table</function> ( <parameter>string</parameter> <type>text</type>, <parameter>delimiter</parameter> <type>text</type> <optional>, <parameter>null_string</parameter> <type>text</type> </optional> )
<returnvalue>setof text</returnvalue>
</para>
<para>
Splits the <parameter>string</parameter> at occurrences
of <parameter>delimiter</parameter> and returns the resulting fields
as a set of <type>text</type> rows.
If <parameter>delimiter</parameter> is <literal>NULL</literal>,
each character in the <parameter>string</parameter> will become a
separate row of the result.
If <parameter>delimiter</parameter> is an empty string, then
the <parameter>string</parameter> is treated as a single field.
If <parameter>null_string</parameter> is supplied and is
not <literal>NULL</literal>, fields matching that string are
replaced by <literal>NULL</literal>.
</para>
<para>
<literal>string_to_table('xx~^~yy~^~zz', '~^~', 'yy')</literal>
<returnvalue></returnvalue>
<programlisting>
xx
NULL
zz
</programlisting>
</para></entry>
</row>
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
@ -17819,33 +17878,6 @@ SELECT NULLIF(value, '(none)') ...
</para></entry>
</row>
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
<primary>string_to_array</primary>
</indexterm>
<function>string_to_array</function> ( <parameter>string</parameter> <type>text</type>, <parameter>delimiter</parameter> <type>text</type> <optional>, <parameter>null_string</parameter> <type>text</type> </optional> )
<returnvalue>text[]</returnvalue>
</para>
<para>
Splits the <parameter>string</parameter> at occurrences
of <parameter>delimiter</parameter> and forms the remaining data
into a <type>text</type> array.
If <parameter>delimiter</parameter> is <literal>NULL</literal>,
each character in the <parameter>string</parameter> will become a
separate element in the array.
If <parameter>delimiter</parameter> is an empty string, then
the <parameter>string</parameter> is treated as a single field.
If <parameter>null_string</parameter> is supplied and is
not <literal>NULL</literal>, fields matching that string are converted
to <literal>NULL</literal> entries.
</para>
<para>
<literal>string_to_array('xx~~yy~~zz', '~~', 'yy')</literal>
<returnvalue>{xx,NULL,zz}</returnvalue>
</para></entry>
</row>
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>

214
src/backend/utils/adt/varlena.c
View File

@ -26,6 +26,7 @@
#include "lib/hyperloglog.h"
#include "libpq/pqformat.h"
#include "miscadmin.h"
#include "nodes/execnodes.h"
#include "parser/scansup.h"
#include "port/pg_bswap.h"
#include "regex/regex.h"
@ -92,6 +93,17 @@ typedef struct
pg_locale_t locale;
} VarStringSortSupport;
/*
* Output data for split_text(): we output either to an array or a table.
* tupstore and tupdesc must be set up in advance to output to a table.
*/
typedef struct
{
ArrayBuildState *astate;
Tuplestorestate *tupstore;
TupleDesc tupdesc;
} SplitTextOutputData;
/*
* This should be large enough that most strings will fit, but small enough
* that we feel comfortable putting it on the stack
@ -139,7 +151,11 @@ static bytea *bytea_substring(Datum str,
bool length_not_specified);
static bytea *bytea_overlay(bytea *t1, bytea *t2, int sp, int sl);
static void appendStringInfoText(StringInfo str, const text *t);
static Datum text_to_array_internal(PG_FUNCTION_ARGS);
static bool split_text(FunctionCallInfo fcinfo, SplitTextOutputData *tstate);
static void split_text_accum_result(SplitTextOutputData *tstate,
text *field_value,
text *null_string,
Oid collation);
static text *array_to_text_internal(FunctionCallInfo fcinfo, ArrayType *v,
const char *fldsep, const char *null_string);
static StringInfo makeStringAggState(FunctionCallInfo fcinfo);
@ -4564,13 +4580,13 @@ replace_text_regexp(text *src_text, void *regexp,
}
/*
* split_text
* split_part
* parse input string
* return ord item (1 based)
* based on provided field separator
*/
Datum
split_text(PG_FUNCTION_ARGS)
split_part(PG_FUNCTION_ARGS)
{
text *inputstring = PG_GETARG_TEXT_PP(0);
text *fldsep = PG_GETARG_TEXT_PP(1);
@ -4599,7 +4615,6 @@ split_text(PG_FUNCTION_ARGS)
/* empty field separator */
if (fldsep_len < 1)
{
text_position_cleanup(&state);
/* if first field, return input string, else empty string */
if (fldnum == 1)
PG_RETURN_TEXT_P(inputstring);
@ -4679,7 +4694,19 @@ text_isequal(text *txt1, text *txt2, Oid collid)
Datum
text_to_array(PG_FUNCTION_ARGS)
{
return text_to_array_internal(fcinfo);
SplitTextOutputData tstate;
/* For array output, tstate should start as all zeroes */
memset(&tstate, 0, sizeof(tstate));
if (!split_text(fcinfo, &tstate))
PG_RETURN_NULL();
if (tstate.astate == NULL)
PG_RETURN_ARRAYTYPE_P(construct_empty_array(TEXTOID));
PG_RETURN_ARRAYTYPE_P(makeArrayResult(tstate.astate,
CurrentMemoryContext));
}
/*
@ -4693,30 +4720,90 @@ text_to_array(PG_FUNCTION_ARGS)
Datum
text_to_array_null(PG_FUNCTION_ARGS)
{
return text_to_array_internal(fcinfo);
return text_to_array(fcinfo);
}
/*
* common code for text_to_array and text_to_array_null functions
* text_to_table
* parse input string and return table of elements,
* based on provided field separator
*/
Datum
text_to_table(PG_FUNCTION_ARGS)
{
ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
SplitTextOutputData tstate;
MemoryContext old_cxt;
/* check to see if caller supports us returning a tuplestore */
if (rsi == NULL || !IsA(rsi, ReturnSetInfo))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("set-valued function called in context that cannot accept a set")));
if (!(rsi->allowedModes & SFRM_Materialize))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("materialize mode required, but it is not allowed in this context")));
/* OK, prepare tuplestore in per-query memory */
old_cxt = MemoryContextSwitchTo(rsi->econtext->ecxt_per_query_memory);
tstate.astate = NULL;
tstate.tupdesc = CreateTupleDescCopy(rsi->expectedDesc);
tstate.tupstore = tuplestore_begin_heap(true, false, work_mem);
MemoryContextSwitchTo(old_cxt);
(void) split_text(fcinfo, &tstate);
tuplestore_donestoring(tstate.tupstore);
rsi->returnMode = SFRM_Materialize;
rsi->setResult = tstate.tupstore;
rsi->setDesc = tstate.tupdesc;
return (Datum) 0;
}
/*
* text_to_table_null
* parse input string and return table of elements,
* based on provided field separator and null string
*
* This is a separate entry point only to prevent the regression tests from
* complaining about different argument sets for the same internal function.
*/
Datum
text_to_table_null(PG_FUNCTION_ARGS)
{
return text_to_table(fcinfo);
}
/*
* Common code for text_to_array, text_to_array_null, text_to_table
* and text_to_table_null functions.
*
* These are not strict so we have to test for null inputs explicitly.
* Returns false if result is to be null, else returns true.
*
* Note that if the result is valid but empty (zero elements), we return
* without changing *tstate --- caller must handle that case, too.
*/
static Datum
text_to_array_internal(PG_FUNCTION_ARGS)
static bool
split_text(FunctionCallInfo fcinfo, SplitTextOutputData *tstate)
{
text *inputstring;
text *fldsep;
text *null_string;
Oid collation = PG_GET_COLLATION();
int inputstring_len;
int fldsep_len;
char *start_ptr;
text *result_text;
bool is_null;
ArrayBuildState *astate = NULL;
/* when input string is NULL, then result is NULL too */
if (PG_ARGISNULL(0))
PG_RETURN_NULL();
return false;
inputstring = PG_GETARG_TEXT_PP(0);
@ -4743,35 +4830,19 @@ text_to_array_internal(PG_FUNCTION_ARGS)
inputstring_len = VARSIZE_ANY_EXHDR(inputstring);
fldsep_len = VARSIZE_ANY_EXHDR(fldsep);
/* return empty array for empty input string */
/* return empty set for empty input string */
if (inputstring_len < 1)
PG_RETURN_ARRAYTYPE_P(construct_empty_array(TEXTOID));
return true;
/*
* empty field separator: return the input string as a one-element
* array
*/
/* empty field separator: return input string as a one-element set */
if (fldsep_len < 1)
{
Datum elems[1];
bool nulls[1];
int dims[1];
int lbs[1];
/* single element can be a NULL too */
is_null = null_string ? text_isequal(inputstring, null_string, PG_GET_COLLATION()) : false;
elems[0] = PointerGetDatum(inputstring);
nulls[0] = is_null;
dims[0] = 1;
lbs[0] = 1;
/* XXX: this hardcodes assumptions about the text type */
PG_RETURN_ARRAYTYPE_P(construct_md_array(elems, nulls,
1, dims, lbs,
TEXTOID, -1, false, TYPALIGN_INT));
split_text_accum_result(tstate, inputstring,
null_string, collation);
return true;
}
text_position_setup(inputstring, fldsep, PG_GET_COLLATION(), &state);
text_position_setup(inputstring, fldsep, collation, &state);
start_ptr = VARDATA_ANY(inputstring);
@ -4797,16 +4868,12 @@ text_to_array_internal(PG_FUNCTION_ARGS)
chunk_len = end_ptr - start_ptr;
}
/* must build a temp text datum to pass to accumArrayResult */
/* build a temp text datum to pass to split_text_accum_result */
result_text = cstring_to_text_with_len(start_ptr, chunk_len);
is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
/* stash away this field */
astate = accumArrayResult(astate,
PointerGetDatum(result_text),
is_null,
TEXTOID,
CurrentMemoryContext);
split_text_accum_result(tstate, result_text,
null_string, collation);
pfree(result_text);
@ -4821,16 +4888,12 @@ text_to_array_internal(PG_FUNCTION_ARGS)
else
{
/*
* When fldsep is NULL, each character in the inputstring becomes an
* element in the result array. The separator is effectively the
* space between characters.
* When fldsep is NULL, each character in the input string becomes a
* separate element in the result set. The separator is effectively
* the space between characters.
*/
inputstring_len = VARSIZE_ANY_EXHDR(inputstring);
/* return empty array for empty input string */
if (inputstring_len < 1)
PG_RETURN_ARRAYTYPE_P(construct_empty_array(TEXTOID));
start_ptr = VARDATA_ANY(inputstring);
while (inputstring_len > 0)
@ -4839,16 +4902,12 @@ text_to_array_internal(PG_FUNCTION_ARGS)
CHECK_FOR_INTERRUPTS();
/* must build a temp text datum to pass to accumArrayResult */
/* build a temp text datum to pass to split_text_accum_result */
result_text = cstring_to_text_with_len(start_ptr, chunk_len);
is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
/* stash away this field */
astate = accumArrayResult(astate,
PointerGetDatum(result_text),
is_null,
TEXTOID,
CurrentMemoryContext);
split_text_accum_result(tstate, result_text,
null_string, collation);
pfree(result_text);
@ -4857,8 +4916,47 @@ text_to_array_internal(PG_FUNCTION_ARGS)
}
}
PG_RETURN_ARRAYTYPE_P(makeArrayResult(astate,
CurrentMemoryContext));
return true;
}
/*
* Add text item to result set (table or array).
*
* This is also responsible for checking to see if the item matches
* the null_string, in which case we should emit NULL instead.
*/
static void
split_text_accum_result(SplitTextOutputData *tstate,
text *field_value,
text *null_string,
Oid collation)
{
bool is_null = false;
if (null_string && text_isequal(field_value, null_string, collation))
is_null = true;
if (tstate->tupstore)
{
Datum values[1];
bool nulls[1];
values[0] = PointerGetDatum(field_value);
nulls[0] = is_null;
tuplestore_putvalues(tstate->tupstore,
tstate->tupdesc,
values,
nulls);
}
else
{
tstate->astate = accumArrayResult(tstate->astate,
PointerGetDatum(field_value),
is_null,
TEXTOID,
CurrentMemoryContext);
}
}
/*

2
src/include/catalog/catversion.h
View File

@ -53,6 +53,6 @@
*/
/* yyyymmddN */
#define CATALOG_VERSION_NO 202008301
#define CATALOG_VERSION_NO 202009021
#endif

18
src/include/catalog/pg_proc.dat
View File

@ -1561,16 +1561,24 @@
{ oid => '383',
proname => 'array_cat', proisstrict => 'f', prorettype => 'anyarray',
proargtypes => 'anyarray anyarray', prosrc => 'array_cat' },
{ oid => '394', descr => 'split delimited text into text[]',
{ oid => '394', descr => 'split delimited text',
proname => 'string_to_array', proisstrict => 'f', prorettype => '_text',
proargtypes => 'text text', prosrc => 'text_to_array' },
{ oid => '376', descr => 'split delimited text, with null string',
proname => 'string_to_array', proisstrict => 'f', prorettype => '_text',
proargtypes => 'text text text', prosrc => 'text_to_array_null' },
{ oid => '8432', descr => 'split delimited text',
proname => 'string_to_table', proisstrict => 'f', prorows => '1000',
proretset => 't', prorettype => 'text', proargtypes => 'text text',
prosrc => 'text_to_table' },
{ oid => '8433', descr => 'split delimited text, with null string',
proname => 'string_to_table', proisstrict => 'f', prorows => '1000',
proretset => 't', prorettype => 'text', proargtypes => 'text text text',
prosrc => 'text_to_table_null' },
{ oid => '395',
descr => 'concatenate array elements, using delimiter, into text',
proname => 'array_to_string', provolatile => 's', prorettype => 'text',
proargtypes => 'anyarray text', prosrc => 'array_to_text' },
{ oid => '376', descr => 'split delimited text into text[], with null string',
proname => 'string_to_array', proisstrict => 'f', prorettype => '_text',
proargtypes => 'text text text', prosrc => 'text_to_array_null' },
{ oid => '384',
descr => 'concatenate array elements, using delimiter and null string, into text',
proname => 'array_to_string', proisstrict => 'f', provolatile => 's',
@ -3547,7 +3555,7 @@
prosrc => 'regexp_matches' },
{ oid => '2088', descr => 'split string by field_sep and return field_num',
proname => 'split_part', prorettype => 'text',
proargtypes => 'text text int4', prosrc => 'split_text' },
proargtypes => 'text text int4', prosrc => 'split_part' },
{ oid => '2765', descr => 'split string by pattern',
proname => 'regexp_split_to_table', prorows => '1000', proretset => 't',
prorettype => 'text', proargtypes => 'text text',

108
src/test/regress/expected/arrays.out
View File

@ -1755,6 +1755,114 @@ select string_to_array('1,2,3,4,*,6', ',', '*');
{1,2,3,4,NULL,6}
(1 row)
select v, v is null as "is null" from string_to_table('1|2|3', '|') g(v);
v | is null
---+---------
1 | f
2 | f
3 | f
(3 rows)
select v, v is null as "is null" from string_to_table('1|2|3|', '|') g(v);
v | is null
---+---------
1 | f
2 | f
3 | f
| f
(4 rows)
select v, v is null as "is null" from string_to_table('1||2|3||', '||') g(v);
v | is null
-----+---------
1 | f
2|3 | f
| f
(3 rows)
select v, v is null as "is null" from string_to_table('1|2|3', '') g(v);
v | is null
-------+---------
1|2|3 | f
(1 row)
select v, v is null as "is null" from string_to_table('', '|') g(v);
v | is null
---+---------
(0 rows)
select v, v is null as "is null" from string_to_table('1|2|3', NULL) g(v);
v | is null
---+---------
1 | f
| | f
2 | f
| | f
3 | f
(5 rows)
select v, v is null as "is null" from string_to_table(NULL, '|') g(v);
v | is null
---+---------
(0 rows)
select v, v is null as "is null" from string_to_table('abc', '') g(v);
v | is null
-----+---------
abc | f
(1 row)
select v, v is null as "is null" from string_to_table('abc', '', 'abc') g(v);
v | is null
---+---------
| t
(1 row)
select v, v is null as "is null" from string_to_table('abc', ',') g(v);
v | is null
-----+---------
abc | f
(1 row)
select v, v is null as "is null" from string_to_table('abc', ',', 'abc') g(v);
v | is null
---+---------
| t
(1 row)
select v, v is null as "is null" from string_to_table('1,2,3,4,,6', ',') g(v);
v | is null
---+---------
1 | f
2 | f
3 | f
4 | f
| f
6 | f
(6 rows)
select v, v is null as "is null" from string_to_table('1,2,3,4,,6', ',', '') g(v);
v | is null
---+---------
1 | f
2 | f
3 | f
4 | f
| t
6 | f
(6 rows)
select v, v is null as "is null" from string_to_table('1,2,3,4,*,6', ',', '*') g(v);
v | is null
---+---------
1 | f
2 | f
3 | f
4 | f
| t
6 | f
(6 rows)
select array_to_string(NULL::int4[], ',') IS NULL;
?column?
----------

15
src/test/regress/sql/arrays.sql
View File

@ -544,6 +544,21 @@ select string_to_array('1,2,3,4,,6', ',');
select string_to_array('1,2,3,4,,6', ',', '');
select string_to_array('1,2,3,4,*,6', ',', '*');
select v, v is null as "is null" from string_to_table('1|2|3', '|') g(v);
select v, v is null as "is null" from string_to_table('1|2|3|', '|') g(v);
select v, v is null as "is null" from string_to_table('1||2|3||', '||') g(v);
select v, v is null as "is null" from string_to_table('1|2|3', '') g(v);
select v, v is null as "is null" from string_to_table('', '|') g(v);
select v, v is null as "is null" from string_to_table('1|2|3', NULL) g(v);
select v, v is null as "is null" from string_to_table(NULL, '|') g(v);
select v, v is null as "is null" from string_to_table('abc', '') g(v);
select v, v is null as "is null" from string_to_table('abc', '', 'abc') g(v);
select v, v is null as "is null" from string_to_table('abc', ',') g(v);
select v, v is null as "is null" from string_to_table('abc', ',', 'abc') g(v);
select v, v is null as "is null" from string_to_table('1,2,3,4,,6', ',') g(v);
select v, v is null as "is null" from string_to_table('1,2,3,4,,6', ',', '') g(v);
select v, v is null as "is null" from string_to_table('1,2,3,4,*,6', ',', '*') g(v);
select array_to_string(NULL::int4[], ',') IS NULL;
select array_to_string('{}'::int4[], ',');
select array_to_string(array[1,2,3,4,NULL,6], ',');