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Implement a caching mechanism which avoids tons of "SHOW COLUMNS FROM xyz" queries when navigating in the users-tree.

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This commit is contained in:
Ansgar Becker
2007-06-28 23:52:19 +00:00
parent 4d8c8114b0
commit dba536338c
1 changed files with 51 additions and 1 deletions
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52
source/usermanager.pas
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@ -87,6 +87,7 @@ type
procedure GetResTables; procedure GetResTables;
procedure GetResColumns; procedure GetResColumns;
function getColumnNamesOrValues( which: String = 'columns' ): TStringList; function getColumnNamesOrValues( which: String = 'columns' ): TStringList;
function getPrivColumns( privtable: String ): TDataSet;
private private
@ -96,6 +97,7 @@ type
{ Public declarations } { Public declarations }
User, Host : String; // Remember for setting privileges User, Host : String; // Remember for setting privileges
ZQueryDBs, ZQueryTables, ZQueryColumns, ZQueryUsers: TDataSet; ZQueryDBs, ZQueryTables, ZQueryColumns, ZQueryUsers: TDataSet;
ColumnsUsers, ColumnsDB, ColumnsTables, ColumnsColumns : TDataSet;
end; end;
function UserManagerWindow (AOwner : TComponent; Flags : String = '') : Boolean; function UserManagerWindow (AOwner : TComponent; Flags : String = '') : Boolean;
@ -467,7 +469,8 @@ procedure TUserManagerForm.ShowPrivilegesControls(v, w, y: Boolean);
setlist : TStringList; setlist : TStringList;
tmpstr : String; tmpstr : String;
begin begin
q := Mainform.Childwin.GetResults( 'SHOW COLUMNS FROM '+mainform.mask(privtable)); // Get cached dataset
q := getPrivColumns( privtable );
result := TStringList.Create; result := TStringList.Create;
for i := 0 to q.RecordCount-1 do for i := 0 to q.RecordCount-1 do
begin begin
@ -957,4 +960,51 @@ begin
ZQueryColumns := Mainform.Childwin.GetResults( 'SELECT * FROM '+mainform.mask(PRIVTABLE_COLUMNS)); ZQueryColumns := Mainform.Childwin.GetResults( 'SELECT * FROM '+mainform.mask(PRIVTABLE_COLUMNS));
end; end;
{***
Return and cache column names from privtables
This caching avoids tons of SHOW COLUMNS queries
@param string Name of privileges table
}
function TUserManagerForm.getPrivColumns( privtable: String ): TDataSet;
begin
if privtable = PRIVTABLE_USERS then
begin
if not Assigned(ColumnsUsers) then
ColumnsUsers := Mainform.Childwin.GetResults( 'SHOW COLUMNS FROM '+mainform.mask(privtable));
result := ColumnsUsers;
end
else if privtable = PRIVTABLE_DB then
begin
if not Assigned(ColumnsDB) then
ColumnsDB := Mainform.Childwin.GetResults( 'SHOW COLUMNS FROM '+mainform.mask(privtable));
result := ColumnsDB;
end
else if privtable = PRIVTABLE_TABLES then
begin
if not Assigned(ColumnsTables) then
ColumnsTables := Mainform.Childwin.GetResults( 'SHOW COLUMNS FROM '+mainform.mask(privtable));
result := ColumnsTables;
end
else if privtable = PRIVTABLE_COLUMNS then
begin
if not Assigned(ColumnsColumns) then
ColumnsColumns := Mainform.Childwin.GetResults( 'SHOW COLUMNS FROM '+mainform.mask(privtable));
result := ColumnsColumns;
end
else
begin
result := nil;
end;
// Make sure cursor is set to 1st row
if Assigned(result) then
result.First;
end;
end. end.