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Bug#27287 extractvalue() (and updatexml()) extremely slow for large XML

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Performance improvements made.
ExtractValue for large XML values is now much faster
(about 2000 times faster of 1Mb-long XML values).
This commit is contained in:
bar@mysql.com/bar.myoffice.izhnet.ru
2007-10-09 13:53:39 +05:00
parent 2c12ddc1d4
commit 015c00ccb8
1 changed files with 24 additions and 36 deletions
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60
sql/item_xmlfunc.cc
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@@ -2611,35 +2611,27 @@ typedef struct
uint level;
String *pxml; // parsed XML
uint pos[MAX_LEVEL]; // Tag position stack
uint parent; // Offset of the parent of the current node
} MY_XML_USER_DATA;
/*
Find the parent node
SYNOPSYS
Find the parent node, i.e. a tag or attrubute node on the given level.
RETURN
1 - success
0 - failure
*/
static uint xml_parent_tag(MY_XML_NODE *items, uint nitems, uint level)
static bool
append_node(String *str, MY_XML_NODE *node)
{
if (!nitems)
return 0;
MY_XML_NODE *p, *last= &items[nitems-1];
for (p= last; p >= items; p--)
{
if (p->level == level &&
(p->type == MY_XML_NODE_TAG ||
p->type == MY_XML_NODE_ATTR))
{
return p - items;
}
}
return 0;
/*
If "str" doesn't have space for a new node,
it will allocate two times more space that it has had so far.
(2*len+512) is a heuristic value,
which gave the best performance during tests.
The ideas behind this formula are:
- It allows to have a very small number of reallocs:
about 10 reallocs on a 1Mb-long XML value.
- At the same time, it avoids excessive memory use.
*/
if (str->reserve(sizeof(MY_XML_NODE), 2 * str->length() + 512))
return TRUE;
str->q_append((const char*) node, sizeof(MY_XML_NODE));
return FALSE;
}
@@ -2661,19 +2653,17 @@ extern "C" int xml_enter(MY_XML_PARSER *st,const char *attr, size_t len);
int xml_enter(MY_XML_PARSER *st,const char *attr, size_t len)
{
MY_XML_USER_DATA *data= (MY_XML_USER_DATA*)st->user_data;
MY_XML_NODE *nodes= (MY_XML_NODE*) data->pxml->ptr();
uint numnodes= data->pxml->length() / sizeof(MY_XML_NODE);
uint parent= xml_parent_tag(nodes, numnodes, data->level - 1);
MY_XML_NODE node;
node.parent= data->parent; // Set parent for the new node to old parent
data->parent= numnodes; // Remember current node as new parent
data->pos[data->level]= numnodes;
node.level= data->level++;
node.type= st->current_node_type; // TAG or ATTR
node.beg= attr;
node.end= attr + len;
node.parent= parent;
data->pxml->append((const char*) &node, sizeof(MY_XML_NODE));
return MY_XML_OK;
return append_node(data->pxml, &node) ? MY_XML_ERROR : MY_XML_OK;
}
@@ -2694,18 +2684,14 @@ extern "C" int xml_value(MY_XML_PARSER *st,const char *attr, size_t len);
int xml_value(MY_XML_PARSER *st,const char *attr, size_t len)
{
MY_XML_USER_DATA *data= (MY_XML_USER_DATA*)st->user_data;
MY_XML_NODE *nodes= (MY_XML_NODE*) data->pxml->ptr();
uint numnodes= data->pxml->length() / sizeof(MY_XML_NODE);
uint parent= xml_parent_tag(nodes, numnodes, data->level - 1);
MY_XML_NODE node;
node.parent= data->parent; // Set parent for the new text node to old parent
node.level= data->level;
node.type= MY_XML_NODE_TEXT;
node.beg= attr;
node.end= attr + len;
node.parent= parent;
data->pxml->append((const char*) &node, sizeof(MY_XML_NODE));
return MY_XML_OK;
return append_node(data->pxml, &node) ? MY_XML_ERROR : MY_XML_OK;
}
@@ -2730,6 +2716,7 @@ int xml_leave(MY_XML_PARSER *st,const char *attr, size_t len)
data->level--;
MY_XML_NODE *nodes= (MY_XML_NODE*) data->pxml->ptr();
data->parent= nodes[data->parent].parent;
nodes+= data->pos[data->level];
nodes->tagend= st->cur;
@@ -2760,6 +2747,7 @@ String *Item_xml_str_func::parse_xml(String *raw_xml, String *parsed_xml_buf)
p.flags= MY_XML_FLAG_RELATIVE_NAMES | MY_XML_FLAG_SKIP_TEXT_NORMALIZATION;
user_data.level= 0;
user_data.pxml= parsed_xml_buf;
user_data.parent= 0;
my_xml_set_enter_handler(&p, xml_enter);
my_xml_set_value_handler(&p, xml_value);
my_xml_set_leave_handler(&p, xml_leave);