From 111d8e522b61169393e2698924db07586fdd847f Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Wed, 25 Jun 2003 21:30:34 +0000 Subject: Back out array mega-patch. Joe Conway --- doc/src/sgml/array.sgml | 287 ++---------------------------------------------- doc/src/sgml/func.sgml | 199 +-------------------------------- 2 files changed, 10 insertions(+), 476 deletions(-) (limited to 'doc/src') diff --git a/doc/src/sgml/array.sgml b/doc/src/sgml/array.sgml index a7a05762de3..985a92f7fa1 100644 --- a/doc/src/sgml/array.sgml +++ b/doc/src/sgml/array.sgml @@ -1,4 +1,4 @@ - + Arrays @@ -60,74 +60,14 @@ INSERT INTO sal_emp - - A limitation of the present array implementation is that individual - elements of an array cannot be SQL null values. The entire array can be set - to null, but you can't have an array with some elements null and some - not. - - - This can lead to surprising results. For example, the result of the - previous two inserts looks like this: - -SELECT * FROM sal_emp; - name | pay_by_quarter | schedule --------+---------------------------+-------------------- - Bill | {10000,10000,10000,10000} | {{meeting},{""}} - Carol | {20000,25000,25000,25000} | {{talk},{meeting}} -(2 rows) - - Because the [2][2] element of - schedule is missing in each of the - INSERT statements, the [1][2] - element is discarded. - - - Fixing this is on the to-do list. + A limitation of the present array implementation is that individual + elements of an array cannot be SQL null values. The entire array can be set + to null, but you can't have an array with some elements null and some + not. Fixing this is on the to-do list. - - - The ARRAY expression syntax may also be used: - -INSERT INTO sal_emp - VALUES ('Bill', - ARRAY[10000, 10000, 10000, 10000], - ARRAY[['meeting', 'lunch'], ['','']]); - -INSERT INTO sal_emp - VALUES ('Carol', - ARRAY[20000, 25000, 25000, 25000], - ARRAY[['talk', 'consult'], ['meeting', '']]); -SELECT * FROM sal_emp; - name | pay_by_quarter | schedule --------+---------------------------+------------------------------- - Bill | {10000,10000,10000,10000} | {{meeting,lunch},{"",""}} - Carol | {20000,25000,25000,25000} | {{talk,consult},{meeting,""}} -(2 rows) - - Note that with this syntax, multidimensional arrays must have matching - extents for each dimension. This eliminates the missing-array-elements - problem above. For example: - -INSERT INTO sal_emp - VALUES ('Carol', - ARRAY[20000, 25000, 25000, 25000], - ARRAY[['talk', 'consult'], ['meeting']]); -ERROR: Multidimensional arrays must have array expressions with matching dimensions - - Also notice that string literals are single quoted instead of double quoted. - - - - - The examples in the rest of this section are based on the - ARRAY expression syntax INSERTs. - - - @@ -192,30 +132,11 @@ SELECT schedule[1:2][1] FROM sal_emp WHERE name = 'Bill'; with the same result. An array subscripting operation is always taken to - represent an array slice if any of the subscripts are written in the form + represent an array slice if any of the subscripts are written in the + form lower:upper. A lower bound of 1 is assumed for any subscript where only one value - is specified; another example follows: - -SELECT schedule[1:2][2] FROM sal_emp WHERE name = 'Bill'; - schedule ---------------------------- - {{meeting,lunch},{"",""}} -(1 row) - - - - - Additionally, we can also access a single arbitrary array element of - a one-dimensional array with the array_subscript - function: - -SELECT array_subscript(pay_by_quarter, 2) FROM sal_emp WHERE name = 'Bill'; - array_subscript ------------------ - 10000 -(1 row) - + is specified. @@ -226,23 +147,7 @@ UPDATE sal_emp SET pay_by_quarter = '{25000,25000,27000,27000}' WHERE name = 'Carol'; - or using the ARRAY expression syntax: - - -UPDATE sal_emp SET pay_by_quarter = ARRAY[25000,25000,27000,27000] - WHERE name = 'Carol'; - - - - - Anywhere you can use the curly braces array syntax, - you can also use the ARRAY expression syntax. The - remainder of this section will illustrate only one or the other, but - not both. - - - - An array may also be updated at a single element: + or updated at a single element: UPDATE sal_emp SET pay_by_quarter[4] = 15000 @@ -255,14 +160,6 @@ UPDATE sal_emp SET pay_by_quarter[4] = 15000 UPDATE sal_emp SET pay_by_quarter[1:2] = '{27000,27000}' WHERE name = 'Carol'; - - A one-dimensional array may also be updated with the - array_assign function: - - -UPDATE sal_emp SET pay_by_quarter = array_assign(pay_by_quarter, 4, 15000) - WHERE name = 'Bill'; - @@ -281,88 +178,6 @@ UPDATE sal_emp SET pay_by_quarter = array_assign(pay_by_quarter, 4, 15000) create an array with subscript values running from -2 to 7. - - An array can also be enlarged by using the concatenation operator, - ||. - -SELECT ARRAY[1,2] || ARRAY[3,4]; - ?column? ---------------- - {{1,2},{3,4}} -(1 row) - -SELECT ARRAY[5,6] || ARRAY[[1,2],[3,4]]; - ?column? ---------------------- - {{5,6},{1,2},{3,4}} -(1 row) - - - The concatenation operator allows a single element to be pushed on to the - beginning or end of a one-dimensional array. It also allows two - N-dimensional arrays, or an N-dimensional - and an N+1-dimensional array. In the former case, the two - N-dimension arrays become outer elements of an - N+1-dimensional array. In the latter, the - N-dimensional array is added as either the first or last - outer element of the N+1-dimensional array. - - The array is extended in the direction of the push. Hence, by pushing - onto the beginning of an array with a one-based subscript, a zero-based - subscript array is created: - - -SELECT array_dims(t.f) FROM (SELECT 1 || ARRAY[2,3] AS f) AS t; - array_dims ------------- - [0:2] -(1 row) - - - - - An array can also be enlarged by using the functions - array_prepend, array_append, - or array_cat. The first two only support one-dimensional - arrays, but array_cat supports multidimensional arrays. - - Note that the concatenation operator discussed above is preferred over - direct use of these functions. In fact, the functions are primarily for use - in implementing the concatenation operator. However, they may be directly - useful in the creation of user-defined aggregates. Some examples: - - -SELECT array_prepend(1, ARRAY[2,3]); - array_prepend ---------------- - {1,2,3} -(1 row) - -SELECT array_append(ARRAY[1,2], 3); - array_append --------------- - {1,2,3} -(1 row) - -SELECT array_cat(ARRAY[1,2], ARRAY[3,4]); - array_cat ---------------- - {{1,2},{3,4}} -(1 row) - -SELECT array_cat(ARRAY[[1,2],[3,4]], ARRAY[5,6]); - array_cat ---------------------- - {{1,2},{3,4},{5,6}} -(1 row) - -SELECT array_cat(ARRAY[5,6], ARRAY[[1,2],[3,4]]); - array_cat ---------------------- - {{5,6},{1,2},{3,4}} - - - The syntax for CREATE TABLE allows fixed-length arrays to be defined: @@ -378,16 +193,6 @@ CREATE TABLE tictactoe ( length. - - An alternative syntax for one-dimensional arrays may be used. - pay_by_quarter could have been defined as: - - pay_by_quarter integer ARRAY[4], - - This syntax may only be used with the integer - constant to denote the array size. - - Actually, the current implementation does not enforce the declared number of dimensions either. Arrays of a particular element type are @@ -495,72 +300,6 @@ SELECT * FROM sal_emp WHERE pay_by_quarter **= 10000; is not ignored, however: after skipping leading whitespace, everything up to the next right brace or delimiter is taken as the item value. - - - As illustrated earlier in this chapter, arrays may also be represented - using the ARRAY expression syntax. This representation - of an array value consists of items that are interpreted according to the - I/O conversion rules for the array's element type, plus decoration that - indicates the array structure. The decoration consists of the keyword - ARRAY and square brackets ([ and - ]) around the array values, plus delimiter characters between - adjacent items. The delimiter character is always a comma (,). - When representing multidimensional arrays, the keyword - ARRAY is only necessary for the outer level. For example, - '{{"hello world", "happy birthday"}}' could be written as: - -SELECT ARRAY[['hello world', 'happy birthday']]; - array ------------------------------------- - {{"hello world","happy birthday"}} -(1 row) - - or it also could be written as: - -SELECT ARRAY[ARRAY['hello world', 'happy birthday']]; - array ------------------------------------- - {{"hello world","happy birthday"}} -(1 row) - - - - - A final method to represent an array, is through an - ARRAY sub-select expression. For example: - -SELECT ARRAY(SELECT oid FROM pg_proc WHERE proname LIKE 'bytea%'); - ?column? -------------------------------------------------------------- - {2011,1954,1948,1952,1951,1244,1950,2005,1949,1953,2006,31} -(1 row) - - The sub-select may only return a single column. The - resulting one-dimensional array will have an element for each row in the - sub-select result, with an element type matching that of the sub-select's - target column. - - - - Arrays may be cast from one type to another in similar fashion to other - data types: - - -SELECT ARRAY[1,2,3]::oid[]; - array ---------- - {1,2,3} -(1 row) - -SELECT CAST(ARRAY[1,2,3] AS float8[]); - array ---------- - {1,2,3} -(1 row) - - - - @@ -578,14 +317,6 @@ SELECT CAST(ARRAY[1,2,3] AS float8[]); that would otherwise be taken as array syntax or ignorable white space. - - - The discussion in the preceding paragraph with respect to double quoting does - not pertain to the ARRAY expression syntax. In that case, - each element is quoted exactly as any other literal value of the element type. - - - The array output routine will put double quotes around element values if they are empty strings or contain curly braces, delimiter characters, diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index d092cafa2da..3db3ab34e83 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -1,5 +1,5 @@ @@ -6962,203 +6962,6 @@ SELECT pg_type_is_visible('myschema.widget'::regtype); - - Array Functions - - - shows the operators - available for the array types. - - - - <type>array</type> Operators - - - - Operator - Description - Example - Result - - - - - = - equals - ARRAY[1.1,2.1,3.1]::int[] = ARRAY[1,2,3] - t - - - || - array-to-array concatenation - ARRAY[1,2,3] || ARRAY[4,5,6] - {{1,2,3},{4,5,6}} - - - || - array-to-array concatenation - ARRAY[1,2,3] || ARRAY[[4,5,6],[7,8,9]] - {{1,2,3},{4,5,6},{7,8,9}} - - - || - element-to-array concatenation - 3 || ARRAY[4,5,6] - {3,4,5,6} - - - || - array-to-element concatenation - ARRAY[4,5,6] || 7 - {4,5,6,7} - - - -
- - - shows the functions - available for use with array types. See - for more discussion and examples for the use of these functions. - - - - <type>array</type> Functions - - - - Function - Return Type - Description - Example - Result - - - - - - - array_append - (anyarray, anyelement) - - - anyarray - - append an element to the end of an array, returning - NULL for NULL inputs - - array_append(ARRAY[1,2], 3) - {1,2,3} - - - - - array_cat - (anyarray, anyarray) - - - anyarray - - concatenate two arrays, returning NULL - for NULL inputs - - array_cat(ARRAY[1,2,3], ARRAY[4,5,6]) - {{1,2,3},{4,5,6}} - - - - - array_dims - (anyarray) - - - text - - returns a text representation of array dimension lower and upper bounds, - generating an ERROR for NULL inputs - - array_dims(array[[1,2,3],[4,5,6]]) - [1:2][1:3] - - - - - array_lower - (anyarray, integer) - - - integer - - returns lower bound of the requested array dimension, returning - NULL for NULL inputs - - array_lower(array_prepend(0, ARRAY[1,2,3]), 1) - 0 - - - - - array_prepend - (anyelement, anyarray) - - - anyarray - - append an element to the beginning of an array, returning - NULL for NULL inputs - - array_prepend(1, ARRAY[2,3]) - {1,2,3} - - - - - array_to_string - (anyarray, text) - - - text - - concatenates array elements using provided delimiter, returning - NULL for NULL inputs - - array_to_string(array[1.1,2.2,3.3]::numeric(4,2)[],'~^~') - 1.10~^~2.20~^~3.30 - - - - - array_upper - (anyarray, integer) - - - integer - - returns upper bound of the requested array dimension, returning - NULL for NULL inputs - - array_upper(array_append(ARRAY[1,2,3], 4), 1) - 4 - - - - - string_to_array - (text, text) - - - text[] - - splits string into array elements using provided delimiter, returning - NULL for NULL inputs - - string_to_array('1.10~^~2.20~^~3.30','~^~')::float8[] - {1.1,2.2,3.3} - - - -
- Aggregate Functions -- cgit v1.2.3