Value of Serializability

Value of Serializability

Settings:accounts( number, branchnum, balance);

create clustered index c on accounts(number);

– 100000 rows

– Cold buffer

– Isolation level (SERIALIZABLE or READ COMMITTED)

– SQL Server 7, DB2 v7.1 and Oracle 8i on Windows 2000

– Dual Xeon (550MHz,512Kb), 1Gb RAM, Internal RAID controller from Adaptec (80Mb), 4x18Gb drives (10000RPM), Windows 2000.

Value of Serializability

Concurrent Transactions:– T1: summation query [1 thread]

select sum(balance) from accounts;

– T2: swap balance between two account numbers (in order of scan to avoid deadlocks) [N threads]

valX:=select balance from accounts where number=X;valY:=select balance from accounts where number=Y;update accounts set balance=valX where number=Y?;update accounts set balance=valY where number=X?;

Locking Overhead

Settings:accounts( number, branchnum, balance);

create clustered index c on accounts(number);

– 100000 rows

– Cold buffer

– SQL Server 7, DB2 v7.1 and Oracle 8i on Windows 2000


Locking Overhead

No Concurrent Transactions:– Update [10 000 updates]update accounts set balance = Val;

– Insert [10 000 transactions]insert into accounts values(664366,72255,2296.12);

Counter Facility

Settings:

– default isolation level: READ COMMITTED; Empty tables


accounts( number, branchnum, balance);create clustered index c on accounts(number);

counter ( nextkey );insert into counter values (1);

Counter Facility

No Concurrent Transactions:– System [100 000 inserts, N threads]

• SQL Server 7 (uses Identity column)insert into accounts values (94496,2789);

• Oracle 8iinsert into accounts values (seq.nextval,94496,2789);

– Ad-hoc [100 000 inserts, N threads]begin transaction NextKey:=select nextkey from counter; update counter set nextkey = NextKey+1;commit transactionbegin transaction insert into accounts values(NextKey,?,?);commit transaction

Log IO

Settings:lineitem ( L_ORDERKEY, L_PARTKEY , L_SUPPKEY,

L_LINENUMBER , L_QUANTITY, L_EXTENDEDPRICE , L_DISCOUNT, L_TAX , L_RETURNFLAG, L_LINESTATUS , L_SHIPDATE, L_COMMITDATE, L_RECEIPTDATE, L_SHIPINSTRUCT , L_SHIPMODE , L_COMMENT );

– READ COMMITTED isolation level

– Empty table


Log IO

No Concurrent Transactions:

Insertions [300 000 inserts, 10 threads], e.g., but with values changed:

insert into lineitem values (1,7760,401,1,17,28351.92,0.04,0.02,'N','O','1996-03-13','1996-02-12','1996-03-22','DELIVER IN PERSON','TRUCK','blithely regular ideas caj');

Buffer Size

Settings:employees(ssnum, name, lat, long, hundreds1,

hundreds2);

create clustered index c on employees(lat);– 10 distinct values of lat and long, 100 distinct values of hundreds1

and hundreds2

– 20000000 rows (630 Mb);

– Warm Buffer

– Dual Xeon (550MHz,512Kb), 1Gb RAM, Internal RAID controller from Adaptec (80Mb), 4x18Gb drives (10000 RPM), Windows 2000.

Buffer Size

Queries:– Scan Queryselect sum(long) from employees;

– Multipoint queryselect * from employees where lat = ?;

Scan Performance


L_LINENUMBER , L_QUANTITY, L_EXTENDEDPRICE , L_DISCOUNT, L_TAX , L_RETURNFLAG, L_LINESTATUS , L_SHIPDATE, L_COMMITDATE, L_RECEIPTDATE, L_SHIPINSTRUCT , L_SHIPMODE , L_COMMENT );

– 600 000 rows – Cold Buffer– Dual Xeon (550MHz,512Kb), 1Gb RAM, Internal RAID

controller from Adaptec (80Mb), 4x18Gb drives (10000RPM), Windows 2000.

Scan Performance

Queries:select avg(l_discount) from lineitem;

RAID Levels

Settings:accounts( number, branchnum, balance);create clustered index c on accounts(number);

– 100000 rows

– Cold Buffer


RAID Levels

No Concurrent Transactions:– Read Intensive: select avg(balance) from accounts;

– Write Intensive:insert into accounts values (690466,6840,2272.76);

Controller Cache

Settings:employees(ssnum, name, lat, long, hundreds1,hundreds2);

create clustered index c on employees(hundreds2);

– Employees table partitioned over two disks; Log on a separate disk.

– 200 000 rows per table– Database buffer size limited to 400 Mb.– Dual Xeon (550MHz,512Kb), 1Gb RAM, Internal RAID

controller from Adaptec (80Mb), 4x18Gb drives (10000RPM), Windows 2000.

Controller Cache

No Concurrent Transactions:update employees set lat = long, long = lat where hundreds2 = ?;

– cache friendly: update of 20,000 rows (~90Mb)

– cache unfriendly: update of 200,000 rows (~900Mb)

Index Tuning


hundreds2);

clustered index c on employees(hundreds2) with fillfactor = 100;

nonclustered index nc on employees (hundreds2);

index nc3 on employees (ssnum, name, hundreds2);

index nc4 on employees (hundreds2, ssnum, name);– 1000000 rows ; Cold buffer


Index Tuning

Queries:– Update:

update employees set name = ‘XXX’ where ssnum = ?;– Insert:

insert into employees values (1003505,'polo94064',97.48,84.03,4700.55,3987.2);

– Multipoint query: select * from employees where hundreds = ?;

– Covered query: select ssnum, name, lat from employees;

– Range Query: select * from employees where long between ? and ?;

– Point Query: select * from employees where ssnum = ?

Denormalizing


L_LINENUMBER, L_QUANTITY, L_EXTENDEDPRICE , L_DISCOUNT, L_TAX , L_RETURNFLAG, L_LINESTATUS , L_SHIPDATE, L_COMMITDATE, L_RECEIPTDATE, L_SHIPINSTRUCT , L_SHIPMODE , L_COMMENT );

region( R_REGIONKEY, R_NAME, R_COMMENT );

nation( N_NATIONKEY, N_NAME, N_REGIONKEY, N_COMMENT,);

supplier( S_SUPPKEY, S_NAME, S_ADDRESS, S_NATIONKEY, S_PHONE, S_ACCTBAL, S_COMMENT);

– 600000 rows in lineitem, 25 nations, 5 regions, 500 suppliers

Denormalizing

lineitemdenormalized ( L_ORDERKEY, L_PARTKEY , L_SUPPKEY, L_LINENUMBER, L_QUANTITY, L_EXTENDEDPRICE , L_DISCOUNT, L_TAX , L_RETURNFLAG, L_LINESTATUS , L_SHIPDATE, L_COMMITDATE, L_RECEIPTDATE, L_SHIPINSTRUCT , L_SHIPMODE , L_COMMENT, L_REGIONNAMEL_REGIONNAME);

– 600000 rows in lineitemdenormalized

– Cold Buffer

– Dual Pentium II (450MHz, 512Kb), 512 Mb RAM, 3x18Gb drives (10000RPM), Windows 2000.

Queries on Normalized vs. Denormalized Schemas

Queries:select L_ORDERKEY, L_PARTKEY, L_SUPPKEY, L_LINENUMBER, L_QUANTITY,

L_EXTENDEDPRICE, L_DISCOUNT, L_TAX, L_RETURNFLAG, L_LINESTATUS, L_SHIPDATE, L_COMMITDATE, L_RECEIPTDATE, L_SHIPINSTRUCT, L_SHIPMODE, L_COMMENT, R_NAME

from LINEITEM, REGION, SUPPLIER, NATIONwhereL_SUPPKEY = S_SUPPKEYand S_NATIONKEY = N_NATIONKEYand N_REGIONKEY = R_REGIONKEYand R_NAME = 'EUROPE';

select L_ORDERKEY, L_PARTKEY, L_SUPPKEY, L_LINENUMBER, L_QUANTITY, L_EXTENDEDPRICE, L_DISCOUNT, L_TAX, L_RETURNFLAG, L_LINESTATUS, L_SHIPDATE, L_COMMITDATE, L_RECEIPTDATE, L_SHIPINSTRUCT, L_SHIPMODE, L_COMMENT, L_REGIONNAME

from LINEITEMDENORMALIZEDwhere L_REGIONNAME = 'EUROPE';

Queries

Settings: employee(ssnum, name, dept, salary, numfriends);student(ssnum, name, course, grade);techdept(dept, manager, location);

clustered index i1 on employee (ssnum);nonclustered index i2 on employee (name);nonclustered index i3 on employee (dept);

clustered index i4 on student (ssnum);nonclustered index i5 on student (name);

clustered index i6 on techdept (dept);

– 100000 rows in employee, 100000 students, 10 departments; Cold buffer– Dual Pentium II (450MHz, 512Kb), 512 Mb RAM, 3x18Gb drives

(10000RPM), Windows 2000.

Queries - Views

View Techlocation:create view techlocation as select ssnum, techdept.dept, location from employee, techdept where employee.dept = techdept.dept;

Queries:– Original:

select dept from techlocation where ssnum = ?;

– Rewritten:Select dept from employee where ssnum = ?;

Queries – Correlated SubqueriesQueries:

– Original:select ssnum from employee e1 where salary = (select max(salary) from employee e2 where e2.dept = e1.dept);

– Rewritten:select max(salary) as bigsalary, deptinto TEMP from employee group by dept;

select ssnumfrom employee, TEMPwhere salary = bigsalaryand employee.dept = temp.dept;

Aggregate Maintenance

Settings:orders( ordernum, itemnum, quantity, purchaser, vendor );create clustered index i_order on orders(itemnum);

store( vendor, name );

item(itemnum, price);create clustered index i_item on item(itemnum);

vendorOutstanding( vendor, amount);

storeOutstanding( store, amount);

– 1000000 orders, 10000 stores, 1000 items; Cold buffer– Dual Pentium II (450MHz, 512Kb), 512 Mb RAM, 3x18Gb drives



Triggers for Aggregate Maintenancecreate trigger updateVendorOutstanding on orders for insert asupdate vendorOutstandingset amount =

(select vendorOutstanding.amount+sum(inserted.quantity*item.price)from inserted,itemwhere inserted.itemnum = item.itemnum)

where vendor = (select vendor from inserted) ;

create trigger updateStoreOutstanding on orders for insert asupdate storeOutstandingset amount =

(select storeOutstanding.amount+sum(inserted.quantity*item.price) from inserted,item where inserted.itemnum = item.itemnum)

where store = (select store.name from inserted, store where inserted.vendor = store.vendor) ;


Concurrent Transactions:– Insertions

insert into orders values (1000350,7825,562,'xxxxxx6944','vendor4');

– Queriesselect orders.vendor, sum(orders.quantity*item.price)from orders,itemwhere orders.itemnum = item.itemnumgroup by orders.vendor;

select * from vendorOutstanding;

select store.name, sum(orders.quantity*item.price)from orders,item, storewhere orders.itemnum = item.itemnum

and orders.vendor = store.vendorgroup by store.name;

select * from storeOutstanding;

Superlinearity

Settings:sales( id, itemid, customerid, storeid, amount, quantity);

item (itemid);

customer (customerid);

store (storeid);

successfulsales(id, itemid, customerid, storeid, amount, quantity);

unsuccessfulsales(id, itemid, customerid, storeid, amount, quantity);

tempsales( id, itemid, customerid, storeid, amount,quantity);

Superlinearity

Settings (non-clustering, dense indexes):index s1 on sales(itemid);index s2 on sales(customerid);index s3 on sales(storeid);

index succ on successfulsales(id);index succ1 on successfulsales(itemid);index succ2 on successfulsales(customerid);index succ3 on successfulsales(storeid);

– 1000000 sales, 400000 customers, 40000 items, 1000 stores– Cold buffer– Dual Pentium II (450MHz, 512Kb), 512 Mb RAM, 3x18Gb drives


Superlinearity

Queries:– Insert/delete

insert into successfulsalesselect sales.id, sales.itemid, sales.customerid,

sales.storeid, sales.amount, sales.quantityfrom sales, item, customer, storewhere sales.itemid = item.itemidand sales.customerid = customer.customeridand sales.storeid = store.storeid;

insert into unsuccessfulsales select * from sales;godelete from unsuccessfulsaleswhere id in (select id from successfulsales)

Superlinearity

Queries:– Small batches

DECLARE @Nlow INT;DECLARE @Nhigh INT;DECLARE @INCR INT;set @INCR = 100000set @NLow = 0set @Nhigh = @INCRWHILE (@NLow <= 500000)BEGIN

insert into tempsales select * from sales where id between @NLow and @Nhighset @Nlow = @Nlow + @INCRset @Nhigh = @Nhigh + @INCRdelete from tempsales

where id in (select id from successfulsales);insert into unsuccessfulsales select * from tempsales;delete from tempsales;

END

Superlinearity

Queries:– outerjoin

insert into successfulsalesselect sales.id, item.itemid, customer.customerid, store.storeid, sales.amount,

sales.quantityfrom ((sales left outer join item on sales.itemid = item.itemid)left outer join customer on sales.customerid = customer.customerid)left outer join store on sales.storeid = store.storeid;

insert into unsuccessfulsalesselect *from successfulsaleswhere itemid is nullor customerid is nullor storeid is null;godelete from successfulsaleswhere itemid is nullor customerid is nullor storeid is null

Looping can hurt



– 600 000 rows; warm buffer.


Looping can hurt• Queries:

– No loop:sqlStmt = “select * from lineitem where l_partkey <= 200;”odbc->prepareStmt(sqlStmt);odbc->execPrepared(sqlStmt);

– Loop:sqlStmt = “select * from lineitem where l_partkey = ?;”odbc->prepareStmt(sqlStmt);for (int i=1; i<100; i++){

odbc->bindParameter(1, SQL_INTEGER, i);odbc->execPrepared(sqlStmt);

}

Cursors are Death


hundreds2);

– 100000 rows ; Cold buffer


Cursors are Death

Queries:– No cursor

select * from employees;

– Cursor

DECLARE d_cursor CURSOR FOR select * from employees;

OPEN d_cursorwhile (@@FETCH_STATUS = 0)

BEGIN

FETCH NEXT from d_cursorEND

CLOSE d_cursor

go

Retrieve Needed Columns Only



create index i_nc_lineitem on lineitem (l_orderkey, l_partkey, l_suppkey, l_shipdate, l_commitdate);

– 600 000 rows; warm buffer.


Retrieve Needed Columns Only

Queries:– All

Select * from lineitem;

– Covered subsetSelect l_orderkey, l_partkey, l_suppkey, l_shipdate, l_commitdate from lineitem;

Bulk Loading Data



– Initially the table is empty; 600 000 rows to be inserted (138Mb)


Bulk Loading Data

Oracle 8isqlldr directpath=true control=load_lineitem.ctl data=E:\Data\lineitem.tbl

load data infile "lineitem.tbl"into table LINEITEM appendfields terminated by '|' (

L_ORDERKEY, L_PARTKEY, L_SUPPKEY, L_LINENUMBER, L_QUANTITY, L_EXTENDEDPRICE, L_DISCOUNT, L_TAX, L_RETURNFLAG, L_LINESTATUS, L_SHIPDATE DATE "YYYY-MM-DD", L_COMMITDATE DATE "YYYY-MM-DD", L_RECEIPTDATE DATE "YYYY-MM-DD", L_SHIPINSTRUCT, L_SHIPMODE, L_COMMENT

)

Bulk Loading Data

SQL Server 2000bulk insert lineitem

from "E:\Data\lineitem.tbl"

with

(

TABLOCK,

FIELDTERMINATOR = '|',

ROWTERMINATOR = '\n'

);

Bulk Loading Data

DB2 v7.1LOAD FROM E:\data\lineitem.tbl OF DEL

MODIFIED BY coldel| chardel""

dateformat=""YYYY-MM-DD""

savecount 10000

MESSAGES db2load.msg

INSERT INTO DBTUNING.LINEITEM

STATISTICS NO

INDEXING MODE AUTOSELECT

Ecommerce

Settings:shoppingcart( shopperid, itemid, price, qty);

– 500000 rows; warm buffer


Ecommerce

Concurrent Transactions:– Mix

insert into shoppingcart values (107999,914,870,214);update shoppingcart set Qty = 10 where shopperid = 95047 and itemid = 88636;

delete from shoppingcart where shopperid = 86123 and itemid = 8321;

select shopperid, itemid, qty, price from shoppingcart where shopperid = ?;

– Queries Onlyselect shopperid, itemid, qty, price from shoppingcart where shopperid = ?;

Bitmaps

Settings:lineitem ( L_ORDERKEY, L_PARTKEY , L_SUPPKEY, L_LINENUMBER,

L_QUANTITY, L_EXTENDEDPRICE , L_DISCOUNT, L_TAX , L_RETURNFLAG, L_LINESTATUS , L_SHIPDATE, L_COMMITDATE, L_RECEIPTDATE, L_SHIPINSTRUCT , L_SHIPMODE , L_COMMENT );

create bitmap index b_lin_2 on lineitem(l_returnflag);

create bitmap index b_lin_3 on lineitem(l_linestatus);

create bitmap index b_lin_4 on lineitem(l_linenumber);

– 100000 rows ; cold buffer


Bitmaps

Queries:– 1 attribute

select count(*) from lineitem where l_returnflag = 'N';

– 2 attributesselect count(*) from lineitem where l_returnflag = 'N' and l_linenumber > 3;

– 3 attributesselect count(*) from lineitem where l_returnflag =

'N' and l_linenumber > 3 and l_linestatus = 'F';

Multidimensional Indexes

Settings:create table spatial_facts( a1 int, a2 int, a3 int, a4 int, a5 int, a6 int, a7 int, a8 int, a9 int, a10 int, geom_a3_a7 mdsys.sdo_geometry );create index r_spatialfacts on spatial_facts(geom_a3_a7) indextype is mdsys.spatial_index;create bitmap index b2_spatialfacts on

spatial_facts(a3,a7);

– 500000 rows ; cold buffer– Dual Pentium II (450MHz, 512Kb), 512 Mb RAM, 3x18Gb drives


Multidimensional Indexes

Queries:– Point Queries

select count(*) from fact where a3 = 694014 and a7 = 928878;

select count(*) from spatial_facts where SDO_RELATE(geom_a3_a7, MDSYS.SDO_GEOMETRY(2001, NULL, MDSYS.SDO_POINT_TYPE(694014,928878, NULL), NULL, NULL), 'mask=equal querytype=WINDOW') = 'TRUE';

– Range Queriesselect count(*) from spatial_facts where SDO_RELATE(geom_a3_a7,

mdsys.sdo_geometry(2003,NULL,NULL, mdsys.sdo_elem_info_array(1,1003,3),mdsys.sdo_ordinate_array(10,800000,1000000,1000000)), 'mask=inside querytype=WINDOW') = 'TRUE';

select count(*) from spatial_facts where a3 > 10 and a3 < 1000000 and a7 > 800000 and a7 < 1000000;

Approximations

Settings:– TPC-H schema– Approximations

insert into approxlineitem

select top 6000 *from lineitemwhere l_linenumber = 4;

insert into approxordersselect O_ORDERKEY, O_CUSTKEY, O_ORDERSTATUS, O_TOTALPRICE, O_ORDERDATE, O_ORDERPRIORITY, O_CLERK, O_SHIPPRIORITY, O_COMMENT

from orders, approxlineitemwhere o_orderkey = l_orderkey;

Approximationsinsert into approxsupplierselect distinct S_SUPPKEY,

S_NAME ,S_ADDRESS,S_NATIONKEY,S_PHONE,S_ACCTBAL,S_COMMENT

from approxlineitem, supplierwhere s_suppkey = l_suppkey;

insert into approxpartselect distinct P_PARTKEY,

P_NAME , P_MFGR , P_BRAND , P_TYPE , P_SIZE ,P_CONTAINER , P_RETAILPRICE , P_COMMENT

from approxlineitem, partwhere p_partkey = l_partkey;

insert into approxpartsuppselect distinct PS_PARTKEY,

PS_SUPPKEY,PS_AVAILQTY,PS_SUPPLYCOST,PS_COMMENT

from partsupp, approxpart, approxsupplierwhere ps_partkey = p_partkey and

ps_suppkey = s_suppkey;

insert into approxcustomerselect distinct C_CUSTKEY,

C_NAME ,C_ADDRESS,C_NATIONKEY,C_PHONE ,C_ACCTBAL,C_MKTSEGMENT,C_COMMENT

from customer, approxorderswhere o_custkey = c_custkey;insert into approxregion select * from

region;insert into approxnation select * from

nation;

Approximations

Queries:– Query on lineitemSelect l_returnflag, l_linestatus, sum(l_quantity) as sum_qty,

sum(l_extendedprice) as sum_base_price,

sum(l_extendedprice * (1 - l_discount)) as sum_disc_price,

sum(l_extendedprice * (1 - l_discount) * (1 + l_tax)) as sum_charge,

avg(l_quantity) as avg_qty, avg(l_extendedprice) as avg_price, avg(l_discount) as avg_disc, count(*) as count_order

From lineitem

Where datediff(day, l_shipdate, '1998-12-01') <= '120'

group by l_returnflag, l_linestatus

order by l_returnflag, l_linestatus;

Approximations

Queries:– 6-way joinSelect n_name, avg(l_extendedprice * (1 - l_discount)) as

revenueFrom customer, orders, lineitem, supplier, nation, regionWhere c_custkey = o_custkey

and l_orderkey = o_orderkeyand l_suppkey = s_suppkeyand c_nationkey = s_nationkeyand s_nationkey = n_nationkeyand n_regionkey = r_regionkeyand r_name = 'AFRICA'and o_orderdate >= '1993-01-01'and datediff(year, o_orderdate,'1993-01-01') < 1

group by n_nameorder by revenue desc;

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Value of Serializability

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