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port the lovely search code from postgres; overall it's much better, though mysql chokes on it in extreme cases :S

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git-svn-id: file:///home/shish/svn/shimmie2/trunk@1057 7f39781d-f577-437e-ae19-be835c7a54ca
This commit is contained in:
shish 2008-10-09 02:54:17 +00:00
parent c5f9918977
commit 8eef694168
1 changed files with 62 additions and 63 deletions
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125
core/database.class.php
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@ -252,15 +252,14 @@ class Database {
private function build_search_querylet($terms) {
$tag_querylets = array();
$img_querylets = array();
$positive_tag_count = 0;
$negative_tag_count = 0;
// turn each term into a specific type of querylet
// parse the words that are searched for into
// various types of querylet
foreach($terms as $term) {
$negative = false;
$positive = true;
if((strlen($term) > 0) && ($term[0] == '-')) {
$negative = true;
$positive = false;
$term = substr($term, 1);
}
@ -269,29 +268,17 @@ class Database {
$stpe = new SearchTermParseEvent($term);
send_event($stpe);
if($stpe->is_querylet_set()) {
$img_querylets[] = new ImgQuerylet($stpe->get_querylet(), !$negative);
$img_querylets[] = new ImgQuerylet($stpe->get_querylet(), $positive);
}
else {
$term = str_replace("*", "%", $term);
$term = str_replace("?", "_", $term);
if(!preg_match("/^[%_]+$/", $term)) {
$tag_querylets[] = new TagQuerylet($term, !$negative);
$tag_querylets[] = new TagQuerylet($term, $positive);
}
}
}
// merge all the tag querylets into one generic one
$sql = "0";
$terms = array();
foreach($tag_querylets as $tq) {
$sign = $tq->positive ? "+" : "-";
$sql .= " $sign (tag LIKE ?)";
$terms[] = $tq->tag;
if($sign == "+") $positive_tag_count++;
else $negative_tag_count++;
}
$tag_search = new Querylet($sql, $terms);
// merge all the image metadata searches into one generic querylet
$n = 0;
@ -307,8 +294,8 @@ class Database {
// no tags, do a simple search (+image metadata if we have any)
if($positive_tag_count + $negative_tag_count == 0) {
$query = new Querylet("SELECT images.* FROM images");
if(count($tag_querylets) == 0) {
$query = new Querylet("SELECT images.* FROM images ");
if(strlen($img_search->sql) > 0) {
$query->append_sql(" WHERE ");
@ -317,19 +304,12 @@ class Database {
}
// one positive tag (a common case), do an optimised search
else if($positive_tag_count == 1 && $negative_tag_count == 0) {
$query = new Querylet(
// MySQL is braindead, and does a full table scan on images, running the subquery once for each row -_-
// "{$this->get_images} WHERE images.id IN (SELECT image_id FROM tags WHERE tag LIKE ?) ",
"
SELECT images.*
FROM tags, image_tags, images
WHERE
tag LIKE ?
AND tags.id = image_tags.tag_id
AND image_tags.image_id = images.id
",
$tag_search->variables);
else if(count($tag_querylets) == 1 && $tag_querylets[0]->positive) {
$query = new Querylet("
SELECT images.* FROM images
JOIN image_tags ON images.id = image_tags.image_id
WHERE tag_id = (SELECT tags.id FROM tags WHERE lower(tag) = lower(?))
", array($tag_querylets[0]->tag));
if(strlen($img_search->sql) > 0) {
$query->append_sql(" AND ");
@ -339,36 +319,54 @@ class Database {
// more than one positive tag, or more than zero negative tags
else {
$s_tag_array = array_map("sql_escape", $tag_search->variables);
$s_tag_list = join(', ', $s_tag_array);
$tag_id_array = array();
$positive_tag_id_array = array();
$negative_tag_id_array = array();
$tags_ok = true;
foreach($tag_search->variables as $tag) {
$tag_ids = $this->db->GetCol("SELECT id FROM tags WHERE tag LIKE ?", array($tag));
$tag_id_array = array_merge($tag_id_array, $tag_ids);
$tags_ok = count($tag_ids) > 0;
if(!$tags_ok) break;
}
if($tags_ok) {
$tag_id_list = join(', ', $tag_id_array);
$subquery = new Querylet("
SELECT images.*, SUM({$tag_search->sql}) AS score
FROM images
LEFT JOIN image_tags ON image_tags.image_id = images.id
JOIN tags ON image_tags.tag_id = tags.id
WHERE tags.id IN ({$tag_id_list})
GROUP BY images.id
HAVING score = ?",
array_merge(
$tag_search->variables,
array($positive_tag_count)
)
);
$query = new Querylet("
SELECT *
FROM ({$subquery->sql}) AS images ", $subquery->variables);
foreach($tag_querylets as $tq) {
$tag_ids = $this->db->GetCol("SELECT id FROM tags WHERE lower(tag) = lower(?)", array($tq->tag));
if($tq->positive) {
$positive_tag_id_array = array_merge($positive_tag_id_array, $tag_ids);
$tags_ok = count($tag_ids) > 0;
if(!$tags_ok) break;
}
else {
$negative_tag_id_array = array_merge($negative_tag_id_array, $tag_ids);
}
}
if($tags_ok) {
$have_pos = count($positive_tag_id_array) > 0;
$have_neg = count($negative_tag_id_array) > 0;
$sql = "SELECT images.* FROM images WHERE ";
if($have_pos) {
$positive_tag_id_list = join(', ', $positive_tag_id_array);
$positive_tag_count = count($positive_tag_id_array);
$sql .= "
images.id IN (
SELECT image_id
FROM image_tags
WHERE tag_id IN ($positive_tag_id_list)
GROUP BY image_id
HAVING COUNT(image_id)=$positive_tag_count
)
";
}
if($have_pos && $have_neg) {
$sql .= " AND ";
}
if($have_neg) {
$negative_tag_id_list = join(', ', $negative_tag_id_array);
$sql .= "
images.id NOT IN (
SELECT image_id
FROM image_tags
WHERE tag_id IN ($negative_tag_id_list)
)
";
}
$query = new Querylet($sql);
if(strlen($img_search->sql) > 0) {
$query->append_sql(" WHERE ");
@ -376,7 +374,8 @@ class Database {
}
}
else {
# there are no results, "where 1=0" should shortcut things
# one of the positive tags had zero results, therefor there
# can be no results; "where 1=0" should shortcut things
$query = new Querylet("
SELECT images.*
FROM images