[sqlite] improve performance of sqlite generation by proper PRAGMA

Also, force WAL checkpoint at the end, otherwise the DB might be incomplete.

src/Gargantext/API/Node/Corpus/Export.hs

@@ -28,11 +28,12 @@ import Gargantext.API.Node.Corpus.Export.Types ( Corpus(..), CorpusSQLite(..) )
 import Gargantext.API.Node.Corpus.Export.Utils (getContextNgrams, mkCorpusSQLite, mkCorpusSQLiteData)
 import Gargantext.API.Node.Document.Export.Types qualified as DocumentExport
 import Gargantext.API.Prelude (IsGargServer)
+import Gargantext.API.Routes.Named.Corpus qualified as Named
 import Gargantext.Core.NodeStory
 import Gargantext.Core.Text.Ngrams (NgramsType(..))
 import Gargantext.Core.Types.Main ( ListType(MapTerm) )
 import Gargantext.Database.Admin.Types.Hyperdata.Document ( HyperdataDocument(..) )
-import Gargantext.Database.Admin.Types.Node
+import Gargantext.Database.Admin.Types.Node (Context, CorpusId, ListId, context2node, nodeId2ContextId)
 import Gargantext.Database.Prelude
 import Gargantext.Database.Query.Table.Node ( defaultList )
 import Gargantext.Database.Query.Table.NodeContext (selectDocNodes)
@@ -41,7 +42,6 @@ import Gargantext.Prelude hiding (hash)
 import Gargantext.Prelude.Crypto.Hash (hash)
 import Servant (Headers, Header, addHeader)
 import Servant.Server.Generic (AsServerT)
-import qualified Gargantext.API.Routes.Named.Corpus as Named
 
 --------------------------------------------------
 -- | Hashes are ordered by Set

src/Gargantext/API/Node/Corpus/Export/Types.hs

@@ -87,3 +87,4 @@ data CorpusSQLiteData =
                    , _csd_stop_context_ngrams      :: Map ContextId (Set NgramsTerm)
                    , _csd_candidate_context_ngrams :: Map ContextId (Set NgramsTerm)
                    } deriving (Show, Eq, Generic)
+

src/Gargantext/API/Node/Corpus/Export/Utils.hs

@@ -141,7 +141,9 @@ mkCorpusSQLite (CorpusSQLiteData { .. }) = withTempSQLiteDir $ \(fp, _fname, fpa
     S.withConnection fpath $ \conn -> do
       -- better performance
       -- https://kerkour.com/sqlite-for-servers
-      S.execute_ conn "PRAGMA journal_mode = WAL"
+      S.execute_ conn "PRAGMA journal_mode = WAL"    -- overall, a good idea for sqlite
+      S.execute_ conn "PRAGMA synchronous = NORMAL"  -- faster writes
+      S.execute_ conn "PRAGMA cache_size = 1000000"  -- better memory usage
 
       S.execute_ conn "CREATE TABLE info (key, value);"
       S.execute conn "INSERT INTO info (key, value) VALUES ('gargVersion', ?)" (S.Only $ showVersion _csd_version)
@@ -179,6 +181,10 @@ mkCorpusSQLite (CorpusSQLiteData { .. }) = withTempSQLiteDir $ \(fp, _fname, fpa
                                                       , iso8601Show ctxDate
                                                       , Aeson.encode ctxHyperdata )) <$> _csd_contexts)
 
+      -- Force WAL checkpoint so we don't leave any data in the WAL log
+      -- (we only send the sqlite file, while WAL creates additional index files which would not be sent)
+      S.execute_ conn "PRAGMA wal_checkpoint(FULL)"
+
     bsl <- BSL.readFile fpath
 
     pure $ CorpusSQLite { _cs_bs = bsl }