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Diffstat (limited to 'doc/src/FAQ/FAQ.html')
| -rw-r--r-- | doc/src/FAQ/FAQ.html | 20 |
1 files changed, 9 insertions, 11 deletions
diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html index 585807e6ab9..1123086be9a 100644 --- a/doc/src/FAQ/FAQ.html +++ b/doc/src/FAQ/FAQ.html @@ -534,7 +534,7 @@ A report generator? An embedded query language interface?</H4><P> We have a nice graphical user interface called <I>pgaccess,</I> which is shipped as part of the distribution. <I>Pgaccess</I> also has a report -generator. The Web page is <A HREF= +generator. The Web page is <A HREF="" "http://www.flex.ro/pgaccess">http://www.flex.ro/pgaccess</A><P> We also include <I>ecpg,</I> which is an embedded SQL query language interface for @@ -996,20 +996,18 @@ Type Internal Name Notes "char" char 1 character CHAR(#) bpchar blank padded to the specified fixed length VARCHAR(#) varchar size specifies maximum length, no padding -TEXT text length limited only by maximum row length -BYTEA bytea variable-length array of bytes +TEXT text no specific upper limit on length +BYTEA bytea variable-length byte array (null-safe) </PRE><P> You will see the internal name when examining system catalogs and in some error messages.<P> - -The last four types above are "varlena" types (i.e., the first four bytes -are the length, followed by the data). <I>char(#)</I> allocates the -maximum number of bytes no matter how much data is stored in the field. -<I>text, varchar(#),</I> and <I>bytea</I> all have variable length on the disk, -and because of this, there is a small performance penalty for using -them. Specifically, the penalty is for access to all columns after the -first column of this type.<P> + +The last four types above are "varlena" types (i.e., the first four +bytes on disk are the length, followed by the data). Thus the actual +space used is slightly greater than the declared size. However, these +data types are also subject to compression or being stored out-of-line +by TOAST, so the space on disk might also be less than expected.<P> <H4><A NAME="4.16.1">4.16.1</A>) How do I create a |