Log Record Types for Smart Large Objects

All smart-large-object log records are the SBLOB type. Each smart-large-object log record contains six header columns, described in Logical-Log Record Header; the record subtype; and additional information. The information that appears varies, depending on record subtype.

Table 9 lists all the smart-large-object record types. The Subtype column describes the smart-large-object record type. The Action column indicates the type of database server action that generated the log entry. The Additional Columns and Format columns describe what information appears for each record type.

Table 9. Record Subtypes for Smart Large Objects
Record Subtype	Action	Additional Columns	Format
CHALLOC	Allocate chunk extent.	extent [chk, page, len]	Decimal
flags	Hexadecimal
CHCOMBINE	Combine two pages in the user-data extent list.	chunk number	Decimal
first page	Decimal
second page	Decimal
CHFREE	Frees chunk extent.	extent [chk, page, len]	Decimal
CHSPLIT	Split a page in the user-data extent list.	chunk number	Decimal
UDFET page to split	Decimal
CREATE	Create smart large object.	smart-large-object ID [sbs, chk, page, oid]	Decimal
number of extents in lomaphdr	Decimal
DELETE	Delete a smart large object at commit.	smart-large-object ID [sbs, chk, page, oid]	Decimal
EXTEND	Add extent to an extent list of a smart large object.	smart-large-object ID [sbs, chk, page, oid]	Decimal
extent [chk, page, len]	Decimal
lomap overflow page number	Decimal
HDRUPD	Update smart-large-object header page.	smart-large-object ID [sbs, chk, page, oid]	Decimal
old EOF offset	String
new EOF offset	String
old times	Decimal
new times	Decimal
PDELETE	Queue a smart large object for deletion at commit.	smart-large-object ID [sbs, chk, page, oid]	Decimal
PTRUNC	Queue a smart large object for truncation at commit.	smart-large-object ID [sbs, chk, page, oid]	Decimal
old offset	String
new offset	String
REFCOUNT	Increment or decrement the reference count of a smart large object.	smart-large-object ID [sbs, chk, page, oid]	Decimal
1 if increment; 0 if decrement	Decimal
UDINSERT,	Append new user data.	chunk	Decimal
UDINSERT_LT	page within chunk	Decimal
offset within page	Decimal
data length	Decimal
UDUPAFT,	Update user-data after-image if a UDWRITE is too expensive.	chunk	Decimal
UDUPAFT_LT	page within chunk	Decimal
offset within page	Decimal
data length	Decimal
UDUPBEF,	Update user-data beforeimage if a UDWRITE is too expensive.	chunk	Decimal
UDUPBEF_LT	page within chunk	Decimal
offset within page	Decimal
data length	Decimal
UDWRITE,	Update user data (difference image).	chunk	Decimal
UDWRITE_LT	page within chunk	Decimal
offset within page	Decimal
length before write	Decimal
length after write	Decimal
number of different image pieces	Decimal

Table 9. Record Subtypes for Smart Large Objects

Record
Subtype

Action

Additional Columns

Format

CHALLOC

Allocate chunk extent.

extent [chk, page, len]

Decimal

flags

Hexadecimal

CHCOMBINE

Combine two pages in the user-data extent list.

chunk number

Decimal

first page

Decimal

second page

Decimal

CHFREE

Frees chunk extent.

extent [chk, page, len]

Decimal

CHSPLIT

Split a page in the user-data extent list.

chunk number

Decimal

UDFET page to split

Decimal

CREATE

Create smart large object.

smart-large-object ID
[sbs, chk, page, oid]

Decimal

number of extents in lomaphdr

Decimal

DELETE

Delete a smart large object at commit.

smart-large-object ID
[sbs, chk, page, oid]

Decimal

EXTEND

Add extent to an extent list of a smart large object.

smart-large-object ID
[sbs, chk, page, oid]

Decimal

extent [chk, page, len]

Decimal

lomap overflow page number

Decimal

HDRUPD

Update smart-large-object header page.

smart-large-object ID
[sbs, chk, page, oid]

Decimal

old EOF offset

String

new EOF offset

String

old times

Decimal

new times

Decimal

PDELETE

Queue a smart large object for deletion at commit.

smart-large-object ID [sbs, chk, page, oid]

Decimal

PTRUNC

Queue a smart large object for truncation at commit.

smart-large-object ID
[sbs, chk, page, oid]

Decimal

old offset

String

new offset

String

REFCOUNT

Increment or decrement the reference count of a smart large object.

smart-large-object ID
[sbs, chk, page, oid]

Decimal

1 if increment; 0 if decrement

Decimal

UDINSERT,

Append new user data.

chunk

Decimal

UDINSERT_LT

page within chunk

Decimal

offset within page

Decimal

data length

Decimal

UDUPAFT,

Update user-data after-image if a UDWRITE is too expensive.

chunk

Decimal

UDUPAFT_LT

page within chunk

Decimal

offset within page

Decimal

data length

Decimal

UDUPBEF,

Update user-data beforeimage if a UDWRITE is too expensive.

chunk

Decimal

UDUPBEF_LT

page within chunk

Decimal

offset within page

Decimal

data length

Decimal

UDWRITE,

Update user data (difference image).

chunk

Decimal

UDWRITE_LT

page within chunk

Decimal

offset within page

Decimal

length before write

Decimal

length after write

Decimal

number of different image pieces

Decimal

For an example of smart-large-object records in onlog output, see smart-large-object log records in the chapter on what is the logical log in the IBM Informix Administrator's Guide.

Figure 24 shows an example of smart-large-object records in onlog output. The first two records show that an extent was freed. The next group of records, flanked by BEGIN and COMMIT, shows the allocation of storage and creation of the smart large objects.

Figure 24. Smart-Large-Object Records in onlog Output

addr    len   type   xid       id  link     subtype  specific-info

4e8428   40   SBLOB    8        0  4e7400   CHFREE   (2,53,421)
4e8450   40   SBLOB    8        0  4e8428   CHFREE   (2,579,421)

c8018    40   BEGIN    8        3  0        07/13/98 10:23:04 34       informix
c8040    264  SBLOB    8        0  c8018    CREATE   [2,2,1,900350517]  10
c8148    44   SBLOB    8        0  c8040    CHALLOC  (2,53,8) 0x1
c8174    68   SBLOB    8        0  c8148    EXTEND   [2,2,1,900350517] (2,53,8) -1
c81b8    264  SBLOB    8        0  c8174    CREATE   [2,2,2,900350518]  10
c82c0    44   SBLOB    8        0  c81b8    CHALLOC  (2,61,1) 0x1
c82ec    68   SBLOB    8        0  c82c0    EXTEND   [2,2,2,900350518] (2,61,1) -1
c8330    56   SBLOB    8        0  c82ec    REFCOUNT [2,2,1,900350517] 1
c8368    56   SBLOB    8        0  c8330    REFCOUNT [2,2,2,900350518] 1
c83a0    36   COMMIT   8        0  c8368    07/13/98 10:23:05

c83c4    40   BEGIN    8        3  0        07/13/98 10:23:05 34       informix
c83ec    264  SBLOB    8        0  c83c4    CREATE   [2,2,3,900350519]  10
c84f4    44   SBLOB    8        0  c83ec    CHALLOC  (2,62,1) 0x1
c8520    68   SBLOB    8        0  c84f4    EXTEND   [2,2,3,900350519] (2,62,1) -1
c8564    56   SBLOB    8        0  c8520    REFCOUNT [2,2,3,900350519] 1
c859c    36   COMMIT   8        0  c8564    07/13/98 10:23:05