HW3: Heap-File Page
Instructors: Winston Hsu, Hao-Hua Chu
Fall 2010
This document is supplementary document that was created by referring Minibase Project of Univ. of Wisconsin
The slide refers to http://dblab.kaist.ac.kr/Course/minibase/
Architecture of a DBMS
Query
Query Optimization and Execution
Relation Operators
File and Access Methods
Buffer Management
Disk Space Management
DB
Minibase
• Relational Database Management System (RDBMS)
– made by Wisconsin University for educational purpose
• Independent implementation of each component is
possible
– No pain to implementing whole DBMS
– Suitable to understand the internal architecture of DBMS
• Components
– Parser / Optimizer / Query Processor/ Heap file / B+-tree
index / Buffer pool manager / Disk space management
system
Heap-File Page
• Simple Heap-File Page Structure
– Heap-File Page consists of page information, data area and
slot array.
– Data area in a Heap-File Page is always compacted.
– We assume that the supported record data type is only
character.
• Operations
–
–
–
–
Insert / Delete a record in a heap-file page
Get a first / next record id
Get the data / pointer of a record
Get some information
HFPage Structure
short
short
short
short
PageId
PageId
PageId
Page Information
record
…
…
…
…
…
…
freePtr
Data Area
// -1 if EMPTY SLOT
short length;
// offset from data[0]
short offset;
…
slot[0]
…
…
…
…
…
…
slotCnt;
freePtr;
freeSpace;
type;
prevPage;
nextPage;
curPage;
insertRecord(case 1)
Page Information
record
Page Information
…
…
…
…
record
…
…
…
…
Inserted record
Data Area
empty
slot[0]
Data Area
…
…
…
…
Inserted slot
slot[0]
…
…
…
…
insertRecord(case 2)
Page Information
record
Page Information
…
…
…
record
…
…
…
…
…
Inserted record
Data Area
Data Area
…
…
slot[0]
…
…
…
slot[0]
Inserted slot
…
…
…
deleteRecord
Page Information
Page Information
record
…
Removed
record
…
record
…
…
…
Data Area
Data Area
…
…
…
slot[0]
Removed slot
…
…
…
slot[0]
empty
…
exchangeRecord
Page Information
Page Information
ABC
…
…
…
ABCDE
…
ABCDE
…
ABC
Data Area
Data Area
…
…
…
slot[0]
slot[2]
…
…
…
…
slot[0]
slot[2]
…
Return Values of APIs
• Status insertRecord(char *recPtr, int recLen, RID& rid);
– If there is not enough space for new record, return DONE
• Status firstRecord(RID& firstRid);
– If there is no record in Page, return DONE
• Status nextRecord (RID curRid, RID& nextRid);
– If there is no next record in Page, return DONE
• Others
– if slotNo or pageNo of a record Id and input parameters
are not appropriate, return FAIL
Other
• int HFPage::available_space(void)
– sizeof(slot_t) bytes must be reserved for a new slot and cannot be
used by a new record.
• freePtr specifies the offset of the first free bytes in data[]
– Insert from it
– Modify it when deleting
• Check the output with sample_output
– “dumpPage, this: 0x7fffbcf7fa20” is a pointer value. Ignore it.
– diff your_output sample_output
• If there are any questions, you can post them on ptt.cc /
CSIE_DBMS.
All You have to do
• hfpage.C
Try and Test
• wget
http://mll.csie.ntu.edu.tw/course/database_f
10/assignment/hfpage09.tar.gz
• tar -xvvzf hfpage09.tar.gz
• make
• hfpage
• test_driver.C
– Test code file