1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>sqlite driver misfeatures</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REL="HOME"
TITLE="sqlite driver manual"
HREF="index.html"><LINK
REL="UP"
TITLE="Peculiarities you should know about"
HREF="c136.html"><LINK
REL="PREVIOUS"
TITLE="SQLite (mis)features"
HREF="x139.html"><LINK
REL="NEXT"
TITLE="GNU Free Documentation License"
HREF="copying-fdl.html"></HEAD
><BODY
CLASS="SECT1"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>sqlite driver manual: A libdbi driver using the SQLite embedded database engine</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="x139.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Chapter 4. Peculiarities you should know about</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="copying-fdl.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN215"
>4.2. sqlite driver misfeatures</A
></H1
><P
>And now we have to discuss how successful the sqlite driver is in squeezing the SQLite idea of a database engine into the libdbi framework which was shaped after MySQL and PostgreSQL. Keep in mind that the limitations mentioned here are not intrinsic, that is a sufficient amount of coding might fix these problems eventually.</P
><P
></P
><UL
><LI
><P
>The sqlite driver has not been tested for memory leaks yet. It may leak memory like hell.</P
></LI
><LI
><P
>The typeless nature of SQLite has some nasty consequences. The sqlite driver takes great care to reconstruct the type of a field that you request in a query, but this isn't always successful. Some of the functions that SQLite supports work both on numeric and text data. The sqlite driver currently cannot deduce the field type correctly as it would have to check all arguments of each function. Instead the sqlite driver makes a few assumptions that may be right or wrong in a given case. The affected functions are <CODE
CLASS="FUNCTION"
>coalesce(X,Y,...)</CODE
>, <CODE
CLASS="FUNCTION"
>max(X)</CODE
>, <CODE
CLASS="FUNCTION"
>min(X)</CODE
>, and <CODE
CLASS="FUNCTION"
>count(X)</CODE
>.</P
></LI
><LI
><P
>The sqlite driver currently assumes that the directory separator of your filesystem is a slash (/). This may be wrong on your particular system. It is not a problem for Windows systems as long as the sqlite driver is built with the Cygwin tools (see <TT
CLASS="FILENAME"
>README.win32</TT
>).</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
>Building the sqlite driver on Windows/Cygwin has not been tested yet, but it uses the same procedure as the other libdbi drivers. Chances are that it works.</P
></BLOCKQUOTE
></DIV
></LI
><LI
><P
>Listing tables with the <CODE
CLASS="FUNCTION"
>dbi_conn_get_table_list()</CODE
> libdbi function currently returns only permanent tables. Temporary tables are ignored.</P
></LI
><LI
><P
>The sqlite driver assumes that table and field names do not exceed 128 characters in length, including the trailing \0. I don't know whether SQLite internally has such a limit or not (both MySQL and PostgreSQL have a lower limit). The limit can be increased by changing a single #define in the <TT
CLASS="FILENAME"
>dbd_sqlite.h</TT
> header file.</P
></LI
><LI
><P
>In a few cases, the sqlite driver expects you to type SQL keywords in all lowercase or all uppercase, but not mixed. This holds true for the 'from' in a SELECT statement. Type it either as 'from' or as 'FROM', but refrain from using 'fRoM' or other funny mixtures of uppercase and lowercase. Most other database engines treat the keywords as case-insensitive and would accept all variants.</P
></LI
></UL
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="x139.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="copying-fdl.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>SQLite (mis)features</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="c136.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>GNU Free Documentation License</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
|
