Re: array support patch phase 1 patch

Tom Lane wrote:
> I've applied much but not all of this.  Some comments:

Here (finally!) is a doc patch to go with the previously applied array 
support changes. If there are no objections, please apply.

Thanks,

Joe
Index: doc/src/sgml/array.sgml
===================================================================
RCS file: /opt/src/cvs/pgsql-server/doc/src/sgml/array.sgml,v
retrieving revision 1.25
diff -c -r1.25 array.sgml
*** doc/src/sgml/array.sgml	13 Mar 2003 01:30:26 -0000	1.25
--- doc/src/sgml/array.sgml	4 May 2003 05:14:04 -0000
***************
*** 9,15 ****
  
   
    PostgreSQL allows columns of a table to be
!   defined as variable-length multidimensional arrays. Arrays of any
    built-in type or user-defined type can be created.
   
  
--- 9,15 ----
  
   
    PostgreSQL allows columns of a table to be
!   defined as variable-length multi-dimensional arrays. Arrays of any
    built-in type or user-defined type can be created.
   
  
***************
*** 60,73 ****
  
   
  
   
    
!    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.
    
   
   
  
   
--- 60,133 ----
  
   
  
+  
+   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.
+   
+  
+ 
+  
+   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, multi-dimesion 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:  Multiple dimension 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.
    
   
+ 
   
  
   
***************
*** 132,142 ****
  
  
    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
    lower:upper.
    A lower bound of 1 is assumed for any subscript where only one value
!   is specified.
   
  
   
--- 192,221 ----
  
  
    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
    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)
! 
   
  
   
***************
*** 147,153 ****
      WHERE name = 'Carol';
  
  
!   or updated at a single element:
  
  
  UPDATE sal_emp SET pay_by_quarter[4] = 15000
--- 226,248 ----
      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:
  
  
  UPDATE sal_emp SET pay_by_quarter[4] = 15000
***************
*** 160,165 ****
--- 255,268 ----
  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';
+ 
   
  
   
***************
*** 169,175 ****
    value currently has 4 elements, it will have five elements after an
    update that assigns to array[5]</>.  Currently, enlargement in
    this fashion is only allowed for one-dimensional arrays, not
!   multidimensional arrays.
   
  
   
--- 272,278 ----
    value currently has 4 elements, it will have five elements after an
    update that assigns to array[5]</>.  Currently, enlargement in
    this fashion is only allowed for one-dimensional arrays, not
!   multi-dimensional arrays.
   
  
   
***************
*** 179,184 ****
--- 282,367 ----
   
  
   
+   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 multi-dimensional arrays.
+   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}}
+ 
+ 
+   array_prepend and array_append
+   work with a one-dimensional array and a single element to be pushed on
+   to the beginning or end of the array, respectively. 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 array_prepend(1, ARRAY[2,3]) AS f) AS t;
+  array_dims
+ ------------
+  [0:2]
+ (1 row)
+ 
+ 
+   array_cat works with either two
+   n</>-dimension arrays, or an n</>-dimension
+   and an n+1</> dimension array. In the former case, the two
+   n</>-dimension arrays become outer elements of an
+   n+1</> dimension array. In the latter, the
+   n</>-dimension array is added as either the first or last
+   outer element of the n+1</> dimension array.
+  
+ 
+  
+   A final method of enlarging arrays is through the concatenation operator,
+   ||, which works exactly as array_cat
+   does.
+ 
+ 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 syntax for CREATE TABLE allows fixed-length
    arrays to be defined:
  
***************
*** 194,199 ****
--- 377,392 ----
   
  
   
+   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
    all considered to be of the same type, regardless of size or number
***************
*** 292,298 ****
     for the array's element type.  (Among the standard data types provided
     in the PostgreSQL distribution, type
     box</> uses a semicolon (;</>) but all the others
!    use comma.)  In a multidimensional array, each dimension (row, plane,
     cube, etc.) gets its own level of curly braces, and delimiters
     must be written between adjacent curly-braced entities of the same level.
     You may write whitespace before a left brace, after a right
--- 485,491 ----
     for the array's element type.  (Among the standard data types provided
     in the PostgreSQL distribution, type
     box</> uses a semicolon (;</>) but all the others
!    use comma.)  In a multi-dimensional array, each dimension (row, plane,
     cube, etc.) gets its own level of curly braces, and delimiters
     must be written between adjacent curly-braced entities of the same level.
     You may write whitespace before a left brace, after a right
***************
*** 300,305 ****
--- 493,564 ----
     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 multi-dimensional 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)
+ 
+ 
+   
+ 
   
  
   
***************
*** 316,321 ****
--- 575,588 ----
     Alternatively, you can use backslash-escaping to protect all data characters
     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
Index: doc/src/sgml/func.sgml
===================================================================
RCS file: /opt/src/cvs/pgsql-server/doc/src/sgml/func.sgml,v
retrieving revision 1.153
diff -c -r1.153 func.sgml
*** doc/src/sgml/func.sgml	1 May 2003 00:57:05 -0000	1.153
--- doc/src/sgml/func.sgml	5 May 2003 00:42:26 -0000
***************
*** 6962,6967 ****
--- 6962,7194 ----
  
    
  
+  
+   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_accum
+       (anyarray, anyelement)
+      
+     
+ 	anyarray
+ 	
+      append an element to the end of an array, ignoring
+      NULL elements, and creating an array if needed
+     
+ 	array_accum(null, 1)
+ 	{1}
+        
+        
+ 	
+      
+       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_assign
+       (anyarray, integer, anyelement)
+      
+     
+ 	anyarray
+ 	
+      assign a value to a specific array element, returning
+      NULL for NULL inputs
+     
+ 	array_assign(ARRAY[1,2,3], 2, 99)
+ 	{1,99,3}
+        
+        
+ 	
+      
+       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_subscript
+       (anyarray, integer)
+      
+     
+ 	anyelement
+ 	
+      returns requested array element, returning
+      NULL for NULL inputs
+     
+ 	array_subscript(ARRAY[1,2,3], 3)
+ 	3
+        
+        
+ 	
+      
+       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
+        
+        
+ 	
+      
+       singleton_array
+       (anyelement)
+      
+     
+ 	anyarray
+ 	
+      create an array from the provided element, returning
+      NULL for NULL inputs
+     
+ 	singleton_array(1)
+ 	{1}
+        
+       
+      
+     
+   
  
   
    Aggregate Functions