From d790821e375623b6c20f04d943401400d263d8e9 Mon Sep 17 00:00:00 2001
From: dakkar <dakkar@thenautilus.net>
Date: Mon, 8 May 2017 11:51:44 +0100
Subject: maybe faster people migration

---
 lib/Dakkar/TweetArchive/Store.pm | 84 +++++++++++++++++++++++++++-------------
 1 file changed, 58 insertions(+), 26 deletions(-)

diff --git a/lib/Dakkar/TweetArchive/Store.pm b/lib/Dakkar/TweetArchive/Store.pm
index 7dc7e4d..c3840ea 100644
--- a/lib/Dakkar/TweetArchive/Store.pm
+++ b/lib/Dakkar/TweetArchive/Store.pm
@@ -92,7 +92,7 @@ SQL
 sub store_friends($self,$friends) {
     my $ids = $self->_store_people($friends);
 
-    $self->dbh->do(<<"SQL", {}, $json_printer->encode($ids));
+    $self->dbh->do(<<"SQL", {}, $ids);
 INSERT INTO friends(users) VALUES(?)
 SQL
 }
@@ -100,7 +100,7 @@ SQL
 sub store_followers($self,$followers) {
     my $ids = $self->_store_people($followers);
 
-    $self->dbh->do(<<"SQL", {}, $json_printer->encode($ids));
+    $self->dbh->do(<<"SQL", {}, $ids);
 INSERT INTO followers(users) VALUES(?)
 SQL
 }
@@ -171,13 +171,14 @@ SQL
 }
 
 sub _schema_deploy_3($self) {
-    $self->dbh->do(<<'SQL');
+    my $dbh = $self->dbh;
+    $dbh->do(<<'SQL');
 CREATE TABLE people (
   id SERIAL PRIMARY KEY,
   data JSONB NOT NULL
 )
 SQL
-    $self->dbh->do(<<'SQL');
+    $dbh->do(<<'SQL');
 CREATE FUNCTION people_details(data jsonb) RETURNS text[] AS $$
  SELECT array[
    (data->>'id_str'),
@@ -191,33 +192,64 @@ CREATE FUNCTION people_details(data jsonb) RETURNS text[] AS $$
   ];
 $$ LANGUAGE SQL IMMUTABLE RETURNS NULL ON NULL INPUT
 SQL
-    $self->dbh->do(<<'SQL');
+    $dbh->do(<<'SQL');
 CREATE UNIQUE INDEX idx_people ON people (people_details(data))
 SQL
 
-    my $json_parser = JSON::MaybeXS->new();
-
-    my $migrate = sub($table) {
-        $self->dbh->do(<<"SQL");
-DECLARE migrate_crs CURSOR FOR SELECT taken_at,users FROM $table
+    $dbh->do(<<'SQL');
+CREATE TABLE new_followers (
+  taken_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP PRIMARY KEY,
+  users integer[] NOT NULL
+)
 SQL
-        my $fetch = $self->dbh->prepare(q{FETCH 1 FROM migrate_crs});
-        my $update = $self->dbh->prepare(<<"SQL");
-UPDATE $table
-   SET users = ?
- WHERE taken_at = ?
+    $dbh->do(<<'SQL');
+CREATE TABLE new_friends (
+  taken_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT CURRENT_TIMESTAMP PRIMARY KEY,
+  users integer[] NOT NULL
+)
+SQL
+
+    $dbh->do(<<'SQL');
+CREATE OR REPLACE FUNCTION migrate_people() RETURNS VOID AS $$
+DECLARE
+ f RECORD;
+ p RECORD;
+ ids INTEGER[];
+BEGIN
+ FOR f IN SELECT * FROM friends ORDER BY taken_at ASC LOOP
+  RAISE NOTICE 'migrating friends at %s', f.taken_at;
+  ids := '{}';
+  FOR p IN INSERT INTO people(data)
+    SELECT v FROM jsonb_array_elements(f.users) AS d(v)
+    on CONFLICT (people_details(data)) DO UPDATE
+    SET data=EXCLUDED.data
+    RETURNING id LOOP
+   ids := array_append(ids,p.id);
+  END LOOP;
+  INSERT INTO new_friends(taken_at,users) VALUES (f.taken_at,ids);
+ END LOOP;
+
+ FOR f IN SELECT * FROM followers ORDER BY taken_at ASC LOOP
+  RAISE NOTICE 'migrating followers at %s', f.taken_at;
+  ids := '{}';
+  FOR p IN INSERT INTO people(data)
+    SELECT v FROM jsonb_array_elements(f.users) AS d(v)
+    ON CONFLICT (people_details(data)) DO UPDATE
+    SET data=EXCLUDED.data
+    RETURNING id LOOP
+   ids := array_append(ids,p.id);
+  END LOOP;
+  INSERT INTO new_followers(taken_at,users) VALUES (f.taken_at,ids);
+ END LOOP;
+END;
+$$ LANGUAGE PLPGSQL;
 SQL
-        $fetch->execute;
-        while (my @row = $fetch->fetchrow_array) {
-            my $friends = $json_parser->decode($row[1]);
-            my $ids = $self->_store_people($friends);
-            $update->execute($json_printer->encode($ids),$row[0]);
-            $fetch->execute;
-        }
-    };
-
-    $migrate->('friends');
-    $migrate->('followers');
+    $dbh->selectall_arrayref(q{SELECT migrate_people()});
+    $dbh->do(q{DROP FUNCTION migrate_people()});
+    $dbh->do(q{DROP TABLE friends});
+    $dbh->do(q{DROP TABLE followers});
+    $dbh->do(q{ALTER TABLE new_friends RENAME TO friends});
+    $dbh->do(q{ALTER TABLE new_followers RENAME TO followers});
 }
 
 1;
-- 
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