Mi sembra che solo l'aggiornamento delle colonne NULL
rilascerà le pagine per il riutilizzo. Ecco una demo di Very Scottish®, per festeggiare che è quasi alle 17:00, EST.
USE tempdb;
DROP TABLE IF EXISTS dbo.RobertBurns;
CREATE TABLE dbo.RobertBurns
(
Id INT IDENTITY(1, 1) PRIMARY KEY CLUSTERED,
Scotch VARCHAR(50),
HaggisAddress VARBINARY(MAX)
);
DECLARE @AddressToAVarbinaryHaggis VARBINARY(MAX);
DECLARE @AddressToAHaggis NVARCHAR(MAX) = N'
Good luck to you and your honest, plump face,
Great chieftain of the pudding race!
Above them all you take your place,
gut, stomach-lining, or intestine,
You''re well worth a grace
as long as my arm.
The overloaded serving tray there you fill,
Your buttocks shaped like a distant hilltop,
Your wooden skewer could be used to fix a mill
if need be,
While through your pores your juices drip
like liquid gold.
His knife see the serving-man clean,
And then cut you up with great skill,
Making a trench in your bright, gushing guts
To form a ditch,
And then, 0h! What a glorious sight!
Warm, steaming, and rich!
Then, spoonful after spoonful, they eagerly eat,
The devil will get the last bit, on they go,
Until all their well-stretched stomachs, by-and-by,
are bent like drums,
Then the head of the family, about to burst,
murmurs “Thank the Lord".
Is there a pretentious soul who, over his French ragout,
Or Italian cuisine that would make a pig sick,
Or French stew that would make that same pig ill
with complete and utter disgust,
Looks down with a sneering, scornful attitude,
on such a meal? (as Haggis)
Poor devil! See him over his trash!
As feeble as a withered bullrush,
His skinny leg no thicker than a thin rope,
His fist the size of a nut,
Through a river or field to travel,
Completely unfit!
But look at the healthy, Haggis-fed person!
The trembling earth respects him as a man!
Put a knife in his fist,
He''ll make it work!
And legs, and arms, and heads will come off,
Like the tops of thistle.
You Powers who look after mankind,
And dish out his bill of fare,
Old Scotland wants no watery, wimpy stuff
That splashes about in little wooden bowls!
But, if You will grant her a grateful prayer,
Give her a Haggis!';
INSERT dbo.RobertBurns (Scotch, HaggisAddress )
SELECT TOP 1000
CASE WHEN x.c % 15 = 0 THEN 'Laphroaig'
WHEN x.c % 5 = 0 THEN 'Lagavulin'
WHEN x.c % 3 = 0 THEN 'Port Ellen'
ELSE 'Ardbeg'
END AS Scotch,
CONVERT(VARBINARY(MAX), REPLICATE(@AddressToAHaggis, x.c % 20 + 1))
FROM (
SELECT ROW_NUMBER() OVER (ORDER BY @@ROWCOUNT) AS c
FROM sys.messages AS m
) AS x;
CREATE INDEX ix_novarbinary ON dbo.RobertBurns (Scotch, Id);
CREATE INDEX ix_yesvarbinary ON dbo.RobertBurns (Scotch, Id) INCLUDE (HaggisAddress);
Con le righe inserite, controlliamo sulle nostre pagine indice.
SELECT OBJECT_NAME(i.object_id) AS table_name,
i.name AS index_name,
MAX(a.used_pages) AS leaf_me_alone
FROM sys.indexes AS i
JOIN sys.partitions AS p
ON p.object_id = i.object_id
AND p.index_id = i.index_id
JOIN sys.allocation_units AS a
ON a.container_id = p.partition_id
WHERE OBJECT_NAME(i.object_id) = 'RobertBurns'
GROUP BY i.object_id, i.index_id, i.name
ORDER BY OBJECT_NAME(i.object_id), i.index_id;
Dopo l'inserimento, ottengo questo. Le pagine effettive possono variare per te.
table_name index_name leaf_me_alone
RobertBurns PK__RobertBu__3214EC074BE633A2 5587
RobertBurns ix_novarbinary 10
RobertBurns ix_yesvarbinary 5581
Usciamo NULL
alcune file!
UPDATE rb
SET rb.HaggisAddress = NULL
FROM dbo.RobertBurns AS rb
WHERE rb.Id % 15 = 0;
E torna alle nostre pagine:
table_name index_name leaf_me_alone
RobertBurns PK__RobertBu__3214EC074BE633A2 5300
RobertBurns ix_novarbinary 10
RobertBurns ix_yesvarbinary 5273
Quindi il conteggio delle pagine è stato ridotto. Huzzah! Per i due indici che toccano i nostri VARBINARY
dati, hanno perso una pagina buncha. Ciò significa che sono di nuovo in circolazione per altri oggetti da utilizzare. Dato che sono in tempdb, probabilmente vengono inghiottiti abbastanza rapidamente da tutte le cose spazzatura che succedono qui.
Ora reinseriamo alcuni dati:
INSERT dbo.RobertBurns (Scotch, HaggisAddress )
SELECT TOP 10 rb.Scotch, rb.HaggisAddress
FROM dbo.RobertBurns AS rb;
E ricontrollare:
table_name index_name leaf_me_alone
RobertBurns PK__RobertBu__3214EC074BE633A2 5330
RobertBurns ix_novarbinary 11
RobertBurns ix_yesvarbinary 5305
La pagina conta un po 'alzata.
Quindi, sembra che non devi fare nulla di troppo folle, o addirittura ridurre il database per riutilizzare lo spazio. Penso DBCC CLEANTABLE
che tu stia confondendo il comportamento di far cadere le colonne e aver bisogno di correre con quello che stai effettivamente facendo.
Spero che sia di aiuto!