Hi,
Using the Subversion 1.7 / 1.8 wc.db schema I get quite different results
from the query planner for several of our queries, where the difference in
performance is quite huge.
For this typical example using 3.8.0.1 only one index component is used:
$ EXPLAIN QUERY PLAN DELETE FROM NODES WHERE wc_id = ?1 AND local_relpath =
?2;
0|0|0|SEARCH TABLE NODES USING COVERING INDEX I_NODES_PARENT (wc_id=?)
While with 3.7.17 two components are used:
$ EXPLAIN QUERY PLAN DELETE FROM NODES WHERE wc_id = ?1 AND local_relpath =
?2;
0|0|0|SEARCH TABLE NODES USING COVERING INDEX sqlite_autoindex_NODES_1
(wc_id=? AND local_relpath=?) (~9 rows)
As currently wc_id is almost always 0 in our database, 3.8.0 will perform a
full table scan while 3.7.17 (and older) just deletes the right record.
If I perform a similar 'SELECT * FROM' instead of 'DELETE FROM', the right
index is used (but not as COVERING of course), while a 'SELECT local_relpath
FROM' shows the same problem as the delete.
This problem appears specific to cases where multiple covering indexes are
found.
Bert
--
Complete schema:
[[
CREATE TABLE REPOSITORY ( id INTEGER PRIMARY KEY AUTOINCREMENT, root
TEXT UNIQUE NOT NULL, uuid TEXT NOT NULL );
CREATE INDEX I_UUID ON REPOSITORY (uuid);
CREATE INDEX I_ROOT ON REPOSITORY (root);
CREATE TABLE WCROOT ( id INTEGER PRIMARY KEY AUTOINCREMENT,
local_abspath TEXT UNIQUE );
CREATE UNIQUE INDEX I_LOCAL_ABSPATH ON WCROOT (local_abspath);
CREATE TABLE PRISTINE ( checksum TEXT NOT NULL PRIMARY KEY, compression
INTEGER, size INTEGER NOT NULL, refcount INTEGER NOT NULL,
md5_checksum TEXT NOT NULL );
CREATE TABLE ACTUAL_NODE ( wc_id INTEGER NOT NULL REFERENCES WCROOT (id),
local_relpath TEXT NOT NULL, parent_relpath TEXT, properties BLOB,
conflict_old TEXT, conflict_new TEXT, conflict_working TEXT,
prop_reject TEXT, changelist TEXT, text_mod TEXT,
tree_conflict_data TEXT, conflict_data BLOB, older_checksum TEXT
REFERENCES PRISTINE (checksum), left_checksum TEXT REFERENCES PRISTINE
(checksum), right_checksum TEXT REFERENCES PRISTINE (checksum), PRIMARY
KEY (wc_id, local_relpath) );
CREATE TABLE LOCK ( repos_id INTEGER NOT NULL REFERENCES REPOSITORY (id),
repos_relpath TEXT NOT NULL, lock_token TEXT NOT NULL, lock_owner
TEXT, lock_comment TEXT, lock_date INTEGER, PRIMARY KEY (repos_id,
repos_relpath) );
CREATE TABLE WORK_QUEUE ( id INTEGER PRIMARY KEY AUTOINCREMENT, work
BLOB NOT NULL );
CREATE TABLE WC_LOCK ( wc_id INTEGER NOT NULL REFERENCES WCROOT (id),
local_dir_relpath TEXT NOT NULL, locked_levels INTEGER NOT NULL DEFAULT
-1, PRIMARY KEY (wc_id, local_dir_relpath) );
CREATE TABLE NODES ( wc_id INTEGER NOT NULL REFERENCES WCROOT (id),
local_relpath TEXT NOT NULL, op_depth INTEGER NOT NULL, parent_relpath
TEXT, repos_id INTEGER REFERENCES REPOSITORY (id), repos_path TEXT,
revision INTEGER, presence TEXT NOT NULL, moved_here INTEGER,
moved_to TEXT, kind TEXT NOT NULL, properties BLOB, depth TEXT,
checksum TEXT REFERENCES PRISTINE (checksum), symlink_target TEXT,
changed_revision INTEGER, changed_date INTEGER, changed_author
TEXT, translated_size INTEGER, last_mod_time INTEGER, dav_cache
BLOB, file_external TEXT, inherited_props BLOB, PRIMARY KEY (wc_id,
local_relpath, op_depth) );
CREATE VIEW NODES_CURRENT AS SELECT * FROM nodes AS n WHERE op_depth =
(SELECT MAX(op_depth) FROM nodes AS n2 WHERE n2.wc_id
= n.wc_id AND n2.local_relpath = n.local_relpath);
CREATE VIEW NODES_BASE AS SELECT * FROM nodes WHERE op_depth = 0;
CREATE TRIGGER nodes_insert_trigger AFTER INSERT ON nodes WHEN NEW.checksum
IS NOT NULL BEGIN UPDATE pristine SET refcount = refcount + 1 WHERE
checksum = NEW.checksum; END;
CREATE TRIGGER nodes_delete_trigger AFTER DELETE ON nodes WHEN OLD.checksum
IS NOT NULL BEGIN UPDATE pristine SET refcount = refcount - 1 WHERE
checksum = OLD.checksum; END;
CREATE TRIGGER nodes_update_checksum_trigger AFTER UPDATE OF checksum ON
nodes WHEN NEW.checksum IS NOT OLD.checksum BEGIN UPDATE pristine SET
refcount = refcount + 1 WHERE checksum = NEW.checksum; UPDATE pristine
SET refcount = refcount - 1 WHERE checksum = OLD.checksum; END;
CREATE TABLE EXTERNALS ( wc_id INTEGER NOT NULL REFERENCES WCROOT (id),
local_relpath TEXT NOT NULL, parent_relpath TEXT NOT NULL, repos_id
INTEGER NOT NULL REFERENCES REPOSITORY (id), presence TEXT NOT NULL,
kind TEXT NOT NULL, def_local_relpath TEXT NOT NULL,
def_repos_relpath TEXT NOT NULL, def_operational_revision TEXT,
def_revision TEXT, PRIMARY KEY (wc_id, local_relpath) );
CREATE UNIQUE INDEX I_EXTERNALS_DEFINED ON EXTERNALS (wc_id,
def_local_relpath,
local_relpath);
CREATE UNIQUE INDEX I_NODES_MOVED ON NODES (wc_id, moved_to, op_depth);
CREATE INDEX I_PRISTINE_MD5 ON PRISTINE (md5_checksum);
CREATE UNIQUE INDEX I_NODES_PARENT ON NODES (wc_id, parent_relpath,
local_relpath, op_depth);
CREATE UNIQUE INDEX I_ACTUAL_PARENT ON ACTUAL_NODE (wc_id, parent_relpath,
local_relpath);
]]
_______________________________________________
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
