Sql-server – Very slow simple INSERT in transaction

insertperformancesql serversql-server-2016transaction

I have I problematic query on my SQL Server where I could not find the problem. I have two simple tables, one for the "Headers" and one for the "Items" (each with an PK column, total of five fields and some of the FKs).

My client application does the following things:

Open a SQL Server transaction
Insert a header row (1-5 msec)
Insert first item row (with PK value of header row as FK – 5000-20000ms!)
Insert second item row (1-5 msec)
Insert n-th item row (1-5 msec)
Commit
Close transaction

Header table has around 2000 entries, Item table around 6000. No additional indexes defined, no triggers. It's a test system, so there's not much other load/locks. I updated the statistics.

The tables at issue are declared as follows:


INSERT INTO MachineParameterDataItems (
  PlantID
, MachineParameterDataHeaderID
, MachineParameterSetConfigID
, Value
)
VALUES (
  @P0
, @P1
, @P2
, CASE WHEN @P3 = -1 THEN NULL ELSE @P4 END
)

Header table:


/****** Object:  Table [dbo].[MachineParameterDataHeaders]    Script Date: 01.04.2019 11:26:14 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[MachineParameterDataHeaders](
    [MachineParameterDataHeaderID] [int] IDENTITY(1,1) NOT NULL,
    [PlantID] [smallint] NOT NULL,
    [MachineParameterSetID] [int] NOT NULL,
    [BatchID] [int] NULL,
    [CreationDateTime] [datetime2](7) NOT NULL,
PRIMARY KEY CLUSTERED 
(
    [MachineParameterDataHeaderID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

ALTER TABLE [dbo].[MachineParameterDataHeaders]  WITH CHECK ADD  CONSTRAINT [FK__MachinePa__Batch__116A8EFB] FOREIGN KEY([BatchID])
REFERENCES [dbo].[Batches] ([BatchID])
GO

ALTER TABLE [dbo].[MachineParameterDataHeaders] CHECK CONSTRAINT [FK__MachinePa__Batch__116A8EFB]
GO

ALTER TABLE [dbo].[MachineParameterDataHeaders]  WITH CHECK ADD  CONSTRAINT [FK__MachinePa__Plant__0F824689] FOREIGN KEY([PlantID])
REFERENCES [dbo].[Plants] ([PlantID])
GO

ALTER TABLE [dbo].[MachineParameterDataHeaders] CHECK CONSTRAINT [FK__MachinePa__Plant__0F824689]
GO

ALTER TABLE [dbo].[MachineParameterDataHeaders]  WITH CHECK ADD  CONSTRAINT [FK__MachineParameterDataHeaders_MachineParameterSets] FOREIGN KEY([MachineParameterSetID])
REFERENCES [dbo].[MachineParameterSets] ([MachineParameterSetID])
GO

ALTER TABLE [dbo].[MachineParameterDataHeaders] CHECK CONSTRAINT [FK__MachineParameterDataHeaders_MachineParameterSets]
GO

Item table:


/****** Object:  Table [dbo].[MachineParameterDataItems]    Script Date: 01.04.2019 11:24:09 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[MachineParameterDataItems](
    [MachineParameterDataItemID] [int] IDENTITY(1,1) NOT NULL,
    [PlantID] [smallint] NOT NULL,
    [MachineParameterDataHeaderID] [int] NOT NULL,
    [Value] [decimal](18, 6) NULL,
    [MachineParameterSetConfigID] [int] NOT NULL,
PRIMARY KEY CLUSTERED 
(
    [MachineParameterDataItemID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO

ALTER TABLE [dbo].[MachineParameterDataItems]  WITH CHECK ADD  CONSTRAINT [FK__MachinePa__Machi__19FFD4FC] FOREIGN KEY([MachineParameterDataHeaderID])
REFERENCES [dbo].[MachineParameterDataHeaders] ([MachineParameterDataHeaderID])
GO

ALTER TABLE [dbo].[MachineParameterDataItems] CHECK CONSTRAINT [FK__MachinePa__Machi__19FFD4FC]
GO

ALTER TABLE [dbo].[MachineParameterDataItems]  WITH CHECK ADD  CONSTRAINT [FK__MachinePa__Plant__190BB0C3] FOREIGN KEY([PlantID])
REFERENCES [dbo].[Plants] ([PlantID])
GO

ALTER TABLE [dbo].[MachineParameterDataItems] CHECK CONSTRAINT [FK__MachinePa__Plant__190BB0C3]
GO

ALTER TABLE [dbo].[MachineParameterDataItems]  WITH CHECK ADD  CONSTRAINT [FK_MachineParameterDataItems_MachineParameterSetConfigs] FOREIGN KEY([MachineParameterSetConfigID])
REFERENCES [dbo].[MachineParameterSetConfigs] ([MachineParameterSetConfigID])
GO

ALTER TABLE [dbo].[MachineParameterDataItems] CHECK CONSTRAINT [FK_MachineParameterDataItems_MachineParameterSetConfigs]
GO

And here's the relevant execution plan.

Does anyone have a clue what the problem could be?

Best Answer

The INSERT of the header row was not in the SQL transaction, so the INSERT of the first item row was locked by that. I don't know if there is some kind of auto-commit after some time, but adding the header INSERT to the SQL transaction solved the problem.

Related Solutions

Postgresql – Postgres multiple joins slow query, how to store default child record

You write:

Each customer can have multiple sites, but only one should be displayed in this list.

Yet, your query retrieves all rows. That would be a point to optimize. But you also do not define which site is to be picked.

Either way, it does not matter much here. Your EXPLAIN shows only 5026 rows for the site scan (5018 for the customer scan). So hardly any customer actually has more than one site. Did you ANALYZE your tables before running EXPLAIN?

From the numbers I see in your EXPLAIN, indexes will give you nothing for this query. Sequential table scans will be the fastest possible way. Half a second is rather slow for 5000 rows, though. Maybe your database needs some general performance tuning?

Maybe the query itself is faster, but "half a second" includes network transfer? EXPLAIN ANALYZE would tell us more.

If this query is your bottleneck, I would suggest you implement a materialized view.

After you provided more information I find that my diagnosis pretty much holds.

The query itself needs 27 ms. Not much of a problem there. "Half a second" was the kind of misunderstanding I had suspected. The slow part is the network transfer (plus ssh encoding / decoding, possibly rendering). You should only retrieve 100 rows, that would solve most of it, even if it means to execute the whole query every time.

If you go the route with a materialized view like I proposed you could add a serial number without gaps to the table plus index on it - by adding a column row_number() OVER (<your sort citeria here>) AS mv_id.

Then you can query:

SELECT *
FROM   materialized_view
WHERE  mv_id >= 2700
AND    mv_id <  2800;

This will perform very fast. LIMIT / OFFSET cannot compete, that needs to compute the whole table before it can sort and pick 100 rows.

pgAdmin timing

When you execute a query from the query tool, the message pane shows something like:

Total query runtime: 62 ms.

And the status line shows the same time. I quote pgAdmin help about that:

The status line will show how long the last query took to complete. If a dataset was returned, not only the elapsed time for server execution is displayed, but also the time to retrieve the data from the server to the Data Output page.

If you want to see the time on the server you need to use SQL EXPLAIN ANALYZE or the built in Shift + F7keyboard shortcut or Query -> Explain analyze. Then, at the bottom of the explain output you get something like this:

Total runtime: 0.269 ms

Sql-server – Parent-Child Tree Hierarchical ORDER

OK, enough brain cells are dead.

SQL Fiddle

WITH cte AS
(
  SELECT 
    [ICFilterID], 
    [ParentID],
    [FilterDesc],
    [Active],
    CAST(0 AS varbinary(max)) AS Level
  FROM [dbo].[ICFilters]
  WHERE [ParentID] = 0
  UNION ALL
  SELECT 
    i.[ICFilterID], 
    i.[ParentID],
    i.[FilterDesc],
    i.[Active],  
    Level + CAST(i.[ICFilterID] AS varbinary(max)) AS Level
  FROM [dbo].[ICFilters] i
  INNER JOIN cte c
    ON c.[ICFilterID] = i.[ParentID]
)

SELECT 
  [ICFilterID], 
  [ParentID],
  [FilterDesc],
  [Active]
FROM cte
ORDER BY [Level];

Best Answer

Related Solutions

Postgresql – Postgres multiple joins slow query, how to store default child record

pgAdmin timing

Sql-server – Parent-Child Tree Hierarchical ORDER

Related Question