Oracle调优与深入之灌水篇

　　之一 ：EVENT: CONTROLF
　　
　　EVENT: CONTROLF　 - Obtaining & Interpreting ControlFile
　　Dumps
　　------------------------------------------------------------------------------
　　
　　ALTER SESSION SET EVENTS 'immediate trace name controlf level 10';
　　~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
　　
　　It is also sometimes useful to: "ALTER DATABASE BACKUP CONTROLFILE TO TRACE".
　　
　　(From Oracle 7.1.x)
　　
　　*DUMP OF CONTROL FILES, Seq # 202417 = 316b1
　　* FILE HEADER:
　　Software vsn=117502976=700f400, Compatibility Vsn=117477376=7009000
　　Db Id=4188500840=f9a77368, Db Name='ECI_RPT'
　　Control Seq=202417=316b1, File size=1238=4d6
　　File Number=0, Blksiz=512, File Type=4
　　==>　　Control Seq　Control file sequence number
　　==>　　File Number　No concept of file no for control files
　　==>　File Size　This files Size (blocks)
　　==>　Blksiz　　This files block size
　　==>　File Type　(See kclearcase/" target="_blank" >cc.h)
　　KCCTYPCF　　1　 * control file *
　　KCCTYPRL　　2　 * redo log file *
　　KCCTYPDF　　3　 * vanilla db data file *
　　KCCTYPBC　　4　 * backup control file *
　　
　　* DATABASE ENTRY:
　　(offset = 0x200, size = 144, max = 1, hi = 1)
　　DF Version: creation=0x700f400 compatable=0x700b000, Date　05/27/95 03:34:38
　　DB Name "ECI_RPT"
　　Database flags = 0x00000147
　　==>　　　 ^^^^^^^^^^^^^^^^^^^(kcc.h)
　　KCCDIMRE 0x0001　* whether media recovery enabled *
　　KCCDICKD 0x0002　* if dictionary must be checked with control file *
　　KCCDIRLR 0x0004　* DB OPEN RESETLOGS required *
　　KCCDIJNK 0x0008　* junk value from beta - do not reuse this flag *
　　KCCDIMRC 0x0010　* was/is last mounted READ_COMPATIBLE *
　　KCCDICNV 0x0020　* control file was just created by convert from v6 *
　　KCCDIIRA 0x0040　* Incomplete Recovery Allowed when resetting logs *
　　KCCDIDBM 0x0080　* K_MLS - on next open DataBase Mac mode *
　　KCCDICCF 0x0100　* Controlfile was created with CREATE CONTROFILE *
　　
　　Incmplt recovery scn: 0.06d3ac0c Resetlogs scn: 0.02811906 count: 0xc99f490
　　==> ^^^ Last Incomplete recovery　　 ^^^ Last Resetlogs
　　Redo Version: creation=0x700f400 compatable=0x700c000
　　#Data files = 204, #Online files = 1
　　==> ^^^ Can derive no of OFFLINE files from these figures.
　　Database checkpoint: Thread=0 scn: 0.00000000
　　Threads: #Enabled=1, #Open=0, Head=0, Tail=0
　　enabled　threads:　01000000 00000000 00000000 00000000 00000000 00000000 ...
　　Max log members = 4, Max data members = 1
　　Log hist = 0, Arch list: Head=0, Tail=0, Force scn: 0.00000000
　　==>　^^^^^^^^^ Size of Log history if being stored
　　
　　* REDO THREAD ENTRIES:
　　(offset = 0x290, size = 92, max = 6, hi = 1)
　　* THREAD #1 - status:0x6 thread links forward:0 back:0
　　==>　　　　　^^^^(kcc.h)
　　KCCRTOPN　0x01　* set if thread is OPeN *
　　KCCRTENB　0x02　* set if thread is ENaBled *
　　KCCRTPUB　0x04　* set if thread is enabled PUBlicly *
　　#logs:3 first:1 last:3 current:3 last used seq#:0x0
　　enabled at scn: 0.00000000 01/01/88 00:00:00
　　Checkpointed at scn: 0.00000000 01/01/88 00:00:00
　　thread:0 rba:(0.0.0)
　　enabled　threads:　00000000 00000000 00000000 00000000 00000000 00000000 ...
　　LOG FILE ENTRIES:
　　(offset = 0x4b8, size = 72, max = 96, hi = 3)
　　* LOG FILE #1:
　　(#　3) /opt/oracle/ECI_RPT/redo_log1.dbf
　　Thread 1 redo log links: forward=2 backward=0
　　siz=0x64000 seq=0x0 hws=0x0 bsz=512 nab=0x0 flg=0x1
　　==> seq=Log Seq no, hws=Hdr write Seq# nab=Next available block (kcc.h)
　　==> flg:　KCCLESPL　 0x0001 * set if log file spooled *
　　KCCLENAL　 0x0002 * set if No more ALocation may be done in log *
　　KCCLEUSM　 0X0004 * if set USe Me as the next log to make current *
　　KCCLECUR　 0x0008 * set if this is the current log *
　　
　　Archive links: fwrd=0 back=0 Prev scn: 0.00000000
　　==>　　　　　　　　　　　　　　　^^^Low SCN of PREVIOUS log
　　Low scn: 0.00000000 01/01/88 00:00:00
　　==> ^^^SCN when log was switched INTO
　　Next scn: 0.00000000 01/01/88 00:00:00
　　==> ^^^SCN After redo in this log (Ie: should == low of NEXT log)
　　...
　　* DATA FILE #1:
　　(#207) /usr/support/oracle/m4/pms505676/system_1_bpk.dbf
　　size=51200 bsize=2048 status=x213 head=207 tail=207 dup=1
　　==>　　　　　　　　　　　^^^^(kcc.h)
　　KCCFESTS 0x0001 * belongs to System TableSpace *
　　KCCFEONL 0x0002 * file is ONLine *
　　KCCFERDE 0x0004 * ReaDing is Enabled *
　　KCCFECGE 0x0008 * ChanGing is Enabled *
　　KCCFEMRR 0x0010 * Media Recovery Required *
　　KCCFEGEM 0x0020 * Generate End hot backup Marker at next open *
　　KCCFECKD 0x0040 * File entry generated by check dictionary *
　　KCCFESOR 0x0080 * Save Offline scn Range at next checkpoint *
　　KCCFERMF 0x0100 * Renamed Missing File *
　　KCCFEGOI 0x0200 * Generate Off-line Immediate marker *
　　
　　Checkpoint cnt:61191 scn: 0.06d3ac0c stop scn: ffff.ffffffff 05/27/95 03:34:39
　　==> Last Checkpoint SCN ^^^^^^^^^^^^^^　^^^ Stop=fff implies OPEN or WARM backup
　　Creation Checkpointed at scn: 0.00000003 12/04/93 06:37:16
　　thread:0 rba:(0.0.0)
　　enabled　threads:　00000000 00000000 00000000 00000000 00000000 00000000
　　00000000 00000000
　　Offline scn: 0.00000000
　　Online Checkpointed at scn: 0.00000000 01/01/88 00:00:00
　　thread:0 rba:(0.0.0)
　　...
　　之二 ：EVENT: FILE_HDRS
　　
　　EVENT: FILE_HDRS　　 - Obtaining & Interpreting File Header
　　Dumps
　　------------------------------------------------------------------------------
　　
　　ALTER SESSION SET EVENTS 'immediate trace name file_hdrs level 10';
　　~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
　　(From Oracle 7.1.x)
　　
　　*DUMP OF DATA FILES: 209 files in database
　　*DATA FILE #1:　------------ NB: Here down is the control file info ---------
　　(#207) /usr/support/oracle/m4/pms505676/system_1_bpk.dbf
　　size=51200 bsize=2048 status=x213 head=207 tail=207 dup=1
　　==>　　　　　　　　　　　^^^^(kcc.h)
　　KCCFESTS 0x0001 * belongs to System TableSpace *
　　KCCFEONL 0x0002 * file is ONLine *
　　KCCFERDE 0x0004 * ReaDing is Enabled *
　　KCCFECGE 0x0008 * ChanGing is Enabled *
　　KCCFEMRR 0x0010 * Media Recovery Required *
　　KCCFEGEM 0x0020 * Generate End hot backup Marker at next open *
　　KCCFECKD 0x0040 * File entry generated by check dictionary *
　　KCCFESOR 0x0080 * Save Offline scn Range at next checkpoint *
　　KCCFERMF 0x0100 * Renamed Missing File *
　　KCCFEGOI 0x0200 * Generate Off-line Immediate marker *
　　
　　Checkpoint cnt:61191 scn: 0.06d3ac0c stop scn: ffff.ffffffff 05/27/95 03:34:39
　　==>　　　　　　　　　　　　　　　　　　^^^Stop=ffff implies OPEN,ABORT or WARM
　　Creation Checkpointed at scn: 0.00000003 12/04/93 06:37:16
　　thread:0 rba:(0.0.0)
　　enabled　threads:　00000000 00000000 00000000 00000000 00000000 00000000 ...
　　Offline scn: 0.00000000
　　Online Checkpointed at scn: 0.00000000 01/01/88 00:00:00
　　thread:0 rba:(0.0.0)
　　enabled　threads:　00000000 00000000 00000000 00000000 00000000 00000000 ...
　　* FILE HEADER:　------------Here down is from the file header------------------
　　Software vsn=117502976=700f400, Compatibility Vsn=117485568=700b000
　　Db Id=4188500840=f9a77368, Db Name='ECI_PD'　 ^^^ Oldest Usable Oracle Vers
　　Control Seq=202416=316b0, File size=51200=c800
　　==>　^^^ Should be <= to Seq# in control file.
　　File Number=1, Blksiz=2048, File Type=3
　　==>　　　　　　　　　　　　　　　^^^^^^^^^^^(kcc.h)
　　KCCTYPCF　　1　 * control file *
　　KCCTYPRL　　2　 * redo log file *
　　KCCTYPDF　　3　 * vanilla db data file *
　　KCCTYPBC　　4　 * backup control file *
　　Creation　 at　 scn: 0.00000003 12/04/93 06:37:16
　　Backup taken at scn: 0.06d3978c 05/27/95 02:15:20 thread:1
　　==>^^^^^ Last ALTER TABLESPACE BEGIN BACKUP
　　reset logs count:0xc99f490 scn: 0.02811906 recovered at 06/21/95 12:14:05
　　==>^^^^^ Last ALTER DATABASE OPEN RESETLOGS
　　status:0x101 root dba:0x04000179 chkpt cnt: 61191 ctl cnt:61190
　　==>^^^^^ (kcv.h)
　　KCVFHHBP　0x01　* hotbackup-in-progress on file (fuzzy file) *
　　KCVFHHBM　0x02　* end hot backup marker encountered *
　　KCVFHOFZ　0x04　* Online FuZzy because it was online and db open *
　　KCVFHCRM　0x08　* crash recovery marker encountered *
　　KCVFHMFZ　0x10　* Media recovery FuZzy - file in media recovery *
　　KCVFHCMF　0x20　* Clear Media recovery Fuzzy at end of recovery *
　　KCVFHSTS　0x100 * system table space. This bit belongs to kcf *
　　KCVFHFMH　0x200 * Freshly Munged Header. resetlogs not finished *
　　Checkpointed at scn: 0.06d3ac0c 05/27/95 03:25:53
　　thread:1 rba:(864.2.0)
　　==>^^^^^ Last Datafile checkpoint & its REDO address.
　　enabled　threads:　01110000 00000000 00000000 00000000 00000000 00000000 ...
　　==>^^^^^^ Threads of redo - thread 1,2 and 3 in use here
　　
　　之三 ：EVENT: REDOHDR
　　
　　EVENT: REDOHDR　　　 - Obtaining & Interpreting Redo Header
　　Dumps
　　------------------------------------------------------------------------------
　　
　　ALTER SESSION SET EVENTS 'immediate trace name redohdr level 10';
　　~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
　　(From Oracle 7.1.x)
　　
　　*DUMP OF LOG FILES: 4 logs in database
　　*LOG FILE #1:
　　(#　1) /dev/usupport/redo2
　　Thread 1 redo log links: forward=2 backward=0
　　siz=0x1800 seq=0x47 hws=0x2 bsz=512 nab=0xffffffff flg=0x8
　　==> hws=Hdr write seq, nab=Next available block,
　　==> flg:　KCCLESPL　 0x0001 * set if log file spooled *
　　KCCLENAL　 0x0002 * set if No more ALocation may be done in log *
　　KCCLEUSM　 0X0004 * if set USe Me as the next log to make current *
　　KCCLECUR　 0x0008 * set if this is the current log *
　　
　　Archive links: fwrd=0 back=0 Prev scn: 275.f1716c52
　　Low scn: 275.f1716c5e 06/21/95 10:30:12
　　Next scn: ffff.ffffffff 06/20/95 14:36:09
　　FILE HEADER:
　　Software vsn=118514176=7106200, Compatibility Vsn=117489664=700c000
　　Db Id=3615166773=d77b1135, Db Name='P716DB'
　　Control Seq=6539=198b, File size=6144=1800
　　File Number=1, Blksiz=512, File Type=2
　　==>　　　　　　　　　　　　　　　^^^^^^^^^^^(kcc.h)
　　KCCTYPCF　　1　 * control file *
　　KCCTYPRL　　2　 * redo log file *
　　KCCTYPDF　　3　 * vanilla db data file *
　　KCCTYPBC　　4　 * backup control file *
　　
　　descrip:"Thread 0001, Seq# 0000000071, SCN 0x0275f1716c5e-0xffffffffffff"
　　thread:1 nab:0xffffffff seq:0x47 hws:0x2 eot:1 dis:0
　　==> hws=Hdr write seq, nab=Next available block,
　　==>　　　　　　　　　　　　　　　　　　　 ^^^(kcrfh.h)
　　KCRFHENOT 0　* NOT end of thread *
　　KCRFHEPUB 1　* End of thread for PUBLIC thread *
　　KCRFHEPVT 2　* End of thread for PRIVATE thread *
　　==> dis=TRUE if thread disabled at end of this log.
　　
　　reset logs count:0xe28f6a6 scn: 275.efd7b37b
　　Low scn: 275.f1716c5e 06/21/95 10:30:12
　　Next scn: ffff.ffffffff 06/20/95 14:36:09
　　Enabled scn: 275.efd7b37b 05/22/95 14:26:45
　　Thread closed scn: 275.f1716c5e 06/21/95 10:30:12
　　
　　之四 ：EVENT: BLOCKDUMP
　　
　　EVENT:　　　- Interpreting
　　------------------------------------------------------------------------------
　　
　　Oracle BLOCK DUMP (Oracle 7.2.x)　 See <Note:33242.1> for Physical Layout
　　~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
　　
　　There is a block header for any blockdump. It determines the format of the
　　rest of the dump. At the head of any Oracle blockdump you should see a
　　block header thus:
　　
　　buffer dba: 0x08000106 inc: 0x00001001 seq: 0x000087ce
　　ver: 1 type: 1=KTU UNDO HEADER
　　
　　==>　 dba　DBA of the block.　See <Note:33311.1>
　　==>　inc　Incarnation number
　　==>　seq　Sequence No
　　==>　 ver　Version number. Should be 1
　　==>　 type　 Block type as defined in k.h:
　　
　　Id　 Type　　　Example
　　~~　 ~~~~　　　~~~~~~~
　　1　= KTU UNDO HEADER　　　　<Note:33187.1>
　　2　= KTU UNDO BLOCK　　 <Note:33186.1>
　　3　= SAVE UNDO HDR
　　4　= SAVE UNDO BLOCK
　　5　= DATA SEG HDR　　　　　<Note:31258.1>
　　6　= KTB MANAGED (with ITL)
　　DATA　　Table data　 <Note:28983.1>
　　Migrated Row:　<Note:33189.1>
　　Cluster　 <Note:52508.1>
　　INDEX　 Branch:　　<Note:41794.1>
　　Leaf:　　<Note:33190.1>
　　Bitmap Leaf:　<Note:41793.1>
　　7　= TEMP DATA (no itl)
　　8　= SORT KEY
　　9　= SORT RUN
　　10 = SEG FREE LIST
　　11 = DATA FILE HDR
　　12 = DATA SEG HDR with Free List Groups
　　13 = Compatibility SEG
　　-- Here onwards are for UNLIMITED EXTENTS --
　　14 = unlimited undo segment header
　　15 = unlimited save undo segment header
　　16 = unlimited data segment header
　　17 = unlimited data segment header with flg blks
　　18 = extent map block
　　
　　19 = backup set piece header
　　20 = backup set directory block
　　21 = control file block
　　22 = segment free list block with #blks in freelists
　　
　　-- Bitmap segments etc.. --
　　
　　23 = bitmapped segment header
　　24 = bitmapped freelist block
　　25 = bitmap index block
　　26 = bitmap block
　　27 = LOB block
　　
　　之五 ：Data Segment Header
　　
　　QREF:　Blockdump - Data Segment Header
　　------------------------------------------------------------------------------
　　
　　This is part of a set of related blockdumps. Where you see <<Note.X.X>>>
　　you can follow the link to see the related information.
　　
　　SEGMENT HEADER BLOCK DUMP　　　　See <Note:28983.1> for the Data Block.
　　~~~~~~~~~~~~~~~~~~~~~~~~~　　　　　　 See <Note:33188.1> for other block types.
　　
　　buffer dba: 0x24000922 inc: 0x00000635 seq: 0x00000007
　　ver: 1 type: 5=DATA SEGMENT HEADER
　　==>　type　Block type. See <Note:33188.1> for other types.
　　
　　nfl = 1, nfb = 1
　　==>　 nfl　No free list
　　==>　nfb　No freelist groups ?
　　
　　EXT CTL:: nex: 1　　　cex: 0　　　ces: 4
　　cbk: 2
　　lock value: U
　　==>　 nex　Number of Extents allocated in the Extent table (below)
　　==>　cex　Current extent　　　 )
　　==>　 cb　Current block in current extent ) High Water Mark
　　==>　ces　Current extent size (blocks)
　　
　　==> Extent Table:
　　EXT TBL:: nbk: 4　　　dba: 0x24000923
　　==>　nbk　Number of blocks available in the extent
　　NB: The first extent has the segment header allocated from it
　　This is really a 5 block extent (block 1 is seg hdr)
　　==>　dba　DBA of first block in the extent
　　
　　==> Free list
　　SEG LST:: flg: USED　 lhd: 0x24000924 ltl: 0x24000924
　　==>　 lhd　Head DBA of free list
　　==>　ltl　Tail DBA of free list
　　
　　==> NB: Not all blocks in an extent are formatted if not yet used.
　　==>　　 Only those on the free list. Blocks in the last extent and NOT
　　==>　　 on the freelist may contain all zeroes
　　
　　之六 ：Blockdump - Data Block
　　
　　>　　　QREF:　Blockdump - Data Block
　　------------------------------------------------------------------------------
　　
　　DATA BLOCK DUMP (Oracle 7.2.x)　　See <Note:33190.1> for INDEX leaf block.
　　~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~　　　　<Note:31258.1> for Segment Header.
　　<Note:33243.1> OS dump of this block.
　　<Note:33188.1> for other block types.
　　
　　Block header dump: dba: 0x24000923
　　Object id on Block? Y
　　seg/obj: 0xc0b　csc: 0x2f0.4045f9ea　itc: 1　　flg: -　　　　　typ: 1 - DATA
　　fsl: 0　fnx: 0x0
　　==>　 Seg/obj　Object ID in dictionary
　　==>　csc　SCN of last block cleanout
　　==>　itc　Number of ITL slots
　　==>　flg　O = On freelist
　　==>　typ　1 = DATA　 2 = INDEX
　　==>　 fsl　ITL TX freelist slot
　　==>　 fnx　DBA of NEXT block on freelist
　　
　　==> Transaction table (below) controls concurrency:
　　==>　Itl　ITL Index no　 (No ITLS determined by INITRANS and MAXTRANS)
　　==>　Xid　Transaction ID (UndoSeg.Slot.Wrap)
　　==>　Uba　Undo Address　 (UndoDBA.SeqNo.RecordNo)
　　==>　Flg　C = Committed　U = Commit Upper Bound　T = Active at CSC
　　B = Rollback of this UBA gives before image of the ITL.
　　Flag combinations include:
　　CB--　Tx is committed, Rollback of this UBA gives prev ITL.
　　----　Active TX - look at RBS header to see if really active
　　--U-　　If lck=0 block is cleaned out with Upper Bound Commit.
　　If lck!=0 (7.3) Scn is FSC.Scnbase. This is delayed logging
　　block cleanout - see <Parameter:DELAYED_LOGGING_BLOCK_CLEANOUTS>
　　The FSC cannot be discarded.
　　==>　Lck　No Rows affected by this transaction
　　==>　Scn/Fsc　Scn=SCN of commited TX, Fsc=Free space credit (bytes)
　　Fsc overlaps the SCN Wrap when present.
　　
　　Itl　　　　　 Xid　　　　　　　　　Uba　　　　 Flag　Lck　　　　Scn/Fsc
　　0x01　 0x0004.00e.0000017f　0x08000592.00a0.0b　----　　2　fsc 0x001d.00000000
　　<<Note:33187.1>>　　　<<Note:33186.1>>　　^2 rows locked
　　
　　data_block_dump
　　===============　　==> First 4 lines are derived
　　tsiz: 0x7b8　　==> Total Data Area size
　　hsiz: 0x1a　　==> Data header size　(16+#tabs*2 + #rows*2)
　　pbl: 0x00635884　　==> ptr to buffer holding the block
　　bdba: 0x24000923　==> Block DBA
　　flag=---------　　==> N=pctfree hit (clusters),F=dont put on freelist
　　K=flushable cluster keys
　　ntab=1　　　==> N tables (>1 for clusters)
　　nrow=4　　　==> N rows
　　frre=-1　　　==> First free row index entry, -1=you have to add one
　　fsbo=0x1a　　==> Free space Begin Offset
　　fseo=0x320　　==> Free space END offset
　　avsp=0x330　　==> Available space in the block
　　tosp=0x34d　　==> Total available space when all TXs commit
　　0xe:pti[0]　nrow=4　offs=0　 ==> N rows for 1st table
　　0x12:pri[0]　offs=0x792　 ==> ROW INDEX　(offset:pri[ROWNUM])
　　0x14:pri[1]　offs=0x766　 ==>　offs==Offset in block.
　　0x16:pri[2]　offs=0x320　 ==>　sffl==Next free slot (Row index number)
　　0x18:pri[3]　offs=0x71c　 ==>　sffl form a chain of free slots, last=-1
　　
　　block_row_dump:
　　tab 0, row 0, @0x792　　 ==> Table 0, row 0, offset
　　tl: 9 fb: --H----- lb: 0x1 cc: 0
　　nrid:　0x24000924.0　　 ==> NEXT rowid for this row. Migrated row.
　　<<Note:33189.1>>
　　==>　 tl　Row size (header+data)
　　==>　 fb　Flag Byte:　 - This is H: head piece of row ONLY
　　K = Cluster Key　(Flags may change meaning
　　if this is set to show HASH cluster)
　　C = Cluster table member
　　H = Head piece of row
　　D = Deleted row
　　F = First data piece
　　L = Last data piece
　　P = First column continues from previous piece
　　N = Last column continues in next piece
　　==>　 lb　Lock Byte - ITL entry that has this row locked
　　(follow XID to segment header to see if its committed)
　　==>　　 cc　Number columns in this row PIECE (not in the ROW)
　　==>
　　==> Depending on flags:
　　==>　nrid　NEXT ROWID for this row
　　==>　hrid　HEAD ROWID for this row
　　
　　tab 0, row 1, @0x766
　　tl: 44 fb: --H-FL-- lb: 0x0 cc: 5 ==> Complete row (Head,First,Last)
　　col　0: [ 4]　52 4f 57 32　　==> VarChar2 data. Use 'unod' to view it.
　　See <<Note:33183.1>>.
　　col　1: [13]　54 52 41 49 4c 49 4e 47 20 4e 55 4c 4c
　　col　2: [ 7]　77 c4 01 01 01 01 01 ==> DATE data. Use 'oranum' to decode.
　　col　3: [ 2]　c4 02　　　 ==> Number data. Use 'oranum' to decode.
　　For 'oranum' see <<Note:33184.1>>
　　col　4: [10]　31 2c 30 30 30 2c 30 30 30 20
　　==>　　 ^^^^ Note: size here is the column length for this PIECE not the COLUMN
　　
　　==> Note there are only 5 columns - trailing columns are assumed NULL
　　
　　tab 0, row 2, @0x320
　　tl: 1020 fb: --H-FL-- lb: 0x1 cc: 6 ==> 1020 bytes long, locked, 6 cols
　　col　0: [ 4]　52 4f 57 33
　　col　1: [11]　42 49 47 20 50 41 44 44 49 4e 47
　　col　2: [ 7]　77 c4 0c 1f 01 01 01
　　col　3: [ 2]　c1 02
　　col　4: [10]　31 20 20 20 20 20 20 20 20 20 ==> CHAR data. Note trailing blanks
　　col　5: [975]
　　58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58
　　58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58
　　.... Repeated many times
　　
　　tab 0, row 3, @0x71c
　　tl: 32 fb: --H-FL-- lb: 0x0 cc: 4　==> 32 bytes long, Full row piece, 4 cols.
　　col　0: [ 4]　52 4f 57 34
　　col　1: [13]　43 48 41 52 20 49 53 20 45 4d 50 54 59
　　col　2: [ 7]　77 c4 0c 1f 01 01 01
　　col　3: [ 1]　80　　　==> '80' is a NULL
　　end_of_block_dump
　　
　　

原文转自：http://www.ltesting.net