Bulk insert from a table to another - sql-server

Question

We have 2 tables in SQL Server 2008 R2. Periodically, we have to insert a batch of records from Table A to Table B. While the inserting, Table B still able to SELECT & UPDATE. Currently, we use INSERT..SELECT to copy from Table A to Table B. But the problem is while inserting, sometimes will cause UPDATE statement to TABLE B timeout.
Is there a better bulk insert solution from a table to another that won't cause blocking?

Answer 1

They most obvious solution is to use smaller batches as Stanley suggested. If this is really not an option you could explore '(transaction level) snapshot isolation.

Answer 2

1 Set the transaction timeout to a large enough value, so that the statement no longer goes in timeout.
2 Use CURSOR and do it row by row
3 Try this way of doing things. Requires a row identifier (IDENTITY for instance), best to have a PK or INDEX on that field:
SET NOCOUNT ON;
CREATE TABLE #A(
row_id INT IDENTITY(1,1) NOT NULL PRIMARY KEY,
data INT NOT NULL
);
CREATE TABLE #B(
row_id INT NOT NULL PRIMARY KEY,
data INT NOT NULL
);
-- TRUNCATE TABLE #B; -- no truncate needed since you just want to add rows, not copy the whole table
DECLARE #batch_size INT;
SET #batch_size = 10000;
DECLARE #from_row_id INT;
DECLARE #to_row_id INT;
-- You would use this to establish the first #from_row_id if you wanted to copy the whole table
-- SELECT
-- #from_row_id=ISNULL(MIN(row_id),-1)
-- FROM
-- #A AS a;
SELECT
#from_row_id=ISNULL(MAX(row_id),-1)
FROM
#B AS b;
IF #from_row_id=-1
SELECT
#from_row_id=ISNULL(MIN(row_id),-1)
FROM
#A AS a;
ELSE
SELECT
#from_row_id=ISNULL(MIN(row_id),-1)
FROM
#A AS a
WHERE
row_id>#from_row_id;
WHILE #from_row_id>=0
BEGIN
SELECT
#to_row_id=ISNULL(MAX(row_id),-1)
FROM
(
SELECT TOP(#batch_size)
row_id
FROM
#A AS a
WHERE
row_id>=#from_row_id
) AS row_ids
IF #to_row_id=-1
BEGIN
INSERT
#B
SELECT
*
FROM
#A AS a
WHERE
row_id>=#from_row_id;
BREAK;
END
ELSE
INSERT
#B
SELECT
*
FROM
#A AS a
WHERE
row_id BETWEEN #from_row_id AND #to_row_id;
SELECT
#from_row_id=ISNULL(MIN(row_id),-1)
FROM
#A AS a
WHERE
row_id>#to_row_id;
END
DROP TABLE #B;
DROP TABLE #A;