From f53869ba6f01d15071d58c0357638c1b7acc0f12 Mon Sep 17 00:00:00 2001
From: Richard Newman <rnewman@twinql.com>
Date: Tue, 9 Aug 2016 16:55:04 -0700
Subject: [PATCH] Minor perf improvement: create idx_tx_lookup_added after
 populating tx_lookup.

---
 src/datomish/db.cljc            | 5 +++++
 src/datomish/sqlite_schema.cljc | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/datomish/db.cljc b/src/datomish/db.cljc
index 3b59a884..85b60aff 100644
--- a/src/datomish/db.cljc
+++ b/src/datomish/db.cljc
@@ -238,6 +238,7 @@
             many?          (memoize (fn [a] (ds/multival? schema a)))
             <exec          (partial s/execute! (:sqlite-connection db))]
         (p :delete-tx-lookup-before
+           (<? (<exec ["DROP INDEX IF EXISTS id_tx_lookup_added"]))
            (<? (<exec ["DELETE FROM tx_lookup"])))
 
         (p :insertions
@@ -303,6 +304,9 @@
              (catch java.sql.SQLException e
                (throw (ex-info "Transaction violates cardinality constraint" {} e))))) ;; TODO: say more about the conflicting datoms.
 
+        (p :create-tx-lookup-indices
+           (<? (<exec ["CREATE INDEX IF NOT EXISTS idx_tx_lookup_added ON tx_lookup (added0)"])))
+
         (p :join
            ;; Fast, only one table walk: lookup by exact eav.
            (p :join-eav
@@ -348,6 +352,7 @@
 
         ;; The lookup table takes space on disk, so we purge it aggressively.
         (p :delete-tx-lookup-after
+           (<? (<exec ["DROP INDEX IF EXISTS id_tx_lookup_added"]))
            (<? (<exec ["DELETE FROM tx_lookup"])))
 
         ;; The transaction has been written -- read it back.  (We index on tx, so the following is fast.)
diff --git a/src/datomish/sqlite_schema.cljc b/src/datomish/sqlite_schema.cljc
index 4e63c472..57542440 100644
--- a/src/datomish/sqlite_schema.cljc
+++ b/src/datomish/sqlite_schema.cljc
@@ -39,8 +39,8 @@
                          rid INTEGER,
                          e INTEGER, a SMALLINT, v BLOB, tx INTEGER, value_type_tag SMALLINT)"
 
-   "CREATE INDEX idx_tx_lookup_added ON tx_lookup (added0)"
-
+   ;; Note that `id_tx_lookup_added` is created and dropped
+   ;; after insertion, which makes insertion slightly faster.
    ;; Prevent overlapping transactions.  TODO: drop added0?
    "CREATE UNIQUE INDEX idx_tx_lookup_eavt ON tx_lookup (e0, a0, v0, added0, value_type_tag0) WHERE sv IS NOT NULL"