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--- sql_analysis [2016/07/21 04:00] – [Presence and count of specific mail headers] daniel
+++ sql_analysis [2019/01/24 17:55] (current) – [Presence and count of specific mail headers] daniel
@@ Line 52: / Line 52: @@
 <code sql>
 select FIELD||':'||arr[1], count(*)
- from (select FIELD, regexp_matches(lines, '(?:^|\n)' || FIELD || ':\s*([^\n]*)\n', 'g') as arr
+ from (select FIELD, regexp_matches(lines, '(?:^|\n)' || FIELD || ':\s*([^\n]*)', 'gi') as arr
        from header,
          (VALUES ('X-Priority'), ('Importance'), ('Precedence'), ('Priority'),
@@ Line 67: / Line 67: @@
 </code>
-====== Messages with specific attachment types ======
+A stricter version, comparing the md5 hashes of bodies (text and html parts) in addition to the headers:
-To retrieve all messages containing pdf files or any image file:
 <code sql>
-select distinct mail_id FROM attachments WHERE content_type='application/pdf' OR content_type like 'image/%';
+select b2.mail_id from body b1, body b2, header h1, header h2
+ where b1.mail_id < b2.mail_id
+ and h1.mail_id = b1.mail_id
+ and h2.mail_id = b2.mail_id
+ and md5(h1.lines) = md5(h2.lines)
+ and md5(b1.bodytext) is not distinct from md5(b2.bodytext)
+ and md5(b1.bodyhtml) is not distinct from md5(b2.bodyhtml);
 </code>
-====== Messages sent or received today  ======
+The ''IS NOT DISTINCT'' comparator behaves as expected when ''bodytext'' or ''bodyhtml'' is NULL, as opposed
-<code>
+to the simple equality operator, for which ''NULL=NULL'' is false
-select mail_id from mail where msg_date>=date_trunc('day',now());
+====== Hierarchical view of tags  ======
+Output a list of tags sorted by hierarchy level and names,
+with an indentation to represent the hierarchy.
+<code sql>
+WITH RECURSIVE tagr(a,_tag_id,name,level) as (
+ select
+  array[row_number() over (order by name)] as a,
+  tag_id,
+  name,
+as level
+ from tags where parent_id is null
+UNION ALL
+ select
+   tagr.a || row_number() over (order by tags.name),
+   tag_id,
+   tags.name,
+   tagr.level+1
+ FROM tags JOIN tagr ON tagr._tag_id=tags.parent_id
+)
+select repeat('   ', level-1) || name from tagr order by a;
 </code>