, 10),
                        ConsistencyLevel.ONE);
        System.out.println("- Size of Column List = " + columnList.size());

        for (Column column : columnList) {
            System.out.println("- Column: (" + new String(column.getName()) + ","
                    + new String(column.getValue()) + ")");
        }

        System.out.println("- All Done. Exit -");
        System.exit(0);
    }

}

Keyspace and Column family that I have created-
create keyspace my_keyspace with placement_strategy = 'org.apache.cassandra.locator.SimpleStrategy' and strategy_options = {replication_factor:1};
use my_keyspace;
create column family users with column_type = 'Standard' and comparator = 'UTF8Type';

A:

You are almost there in your understanding. However, missing some minute details.
So explaining things in a structured way, cassandra write operation life cycle is divided in these steps 

commitlog write 
memtable write
sstable write

Cassandra writes are first written to a commit log (for durability), and then to an in-memory table structure called a memtable. A write is said to successful once it is written to the commit log and memory, so there is very minimal disk I/O at the time of write. When ever the memtable runs out of space, i.e when the number of keys exceed certain limit (128 is default) or when it reaches the time duration (cluster clock), it is being stored into sstable, immutable space (This mechanism is called Flushing). Once writes are done on SSTable, then you can see the corresponding datas in the data folder, in your case its S:\Apache Cassandra\apache-cassandra-1.2.3\storage\data. Each SSTable composes of mainly 2 files - Index file and Data file

Index file contains - Bloom filter and Key-Offset pairs  

Bloom Filter: A Bloom filter, is a space-efficient probabilistic data structure that is used to test whether an element is a member of a set. False positives are possible, but false negatives are not. Cassandra uses bloom filters to save IO when performing a key lookup: each SSTable has a bloom filter associated
, 10), 
                         ConsistencyLevel. ONE); 
         System.out.println("- Size of Column List = " + columnList.size ()); 

         for (Column column: columnList) { 
             System.out.println("- Column: (" + new String(column.getName ()) + ", " 
                     + new String(column.getValue ()) + ") "); 
         } 

         System.out.println("- All Done. Exit - "); 
         System.exit(0); 
     } 

 } 

 Keyspace and Column syndicate that I have created- 
 make keyspace my_keyspace with placement_strategy =' org.apache.cassandra.locator. SimpleStrategy' and strategy_options = { replication_factor:1 }; 
 use my_keyspace; 
 create column family exploiter with column_type =' Standard' and comparator =' UTF8Type'; 

 A: 

 You are almost there in your agreement. However, missing some minute detail. 
 So explaining thing in a structured way, cassandra compose process life cycle is divided in these steps 

 commitlog write 
 memtable write 
 sstable write 

 Cassandra writes are foremost written to a commit log (for durability), and then to an in - memory board structure called a memtable. A write is say to successful once it is write to the commit log and memory, so there is very minimal disk I / O at the meter of write. When ever the memtable runs out of space, i.e when the number of keys exceed certain limit (128 is default) or when it reaches the time duration (cluster clock), it is being stored into sstable, immutable space (This mechanism is called Flushing). Once writes are done on SSTable, then you can see the match datas in the data booklet, in your subject its S:\Apache Cassandra\apache - cassandra-1.2.3\storage\data. Each SSTable composes of chiefly 2 files - Index file and Data file 

 Index file contains - Bloom filter and Key - Offset pairs  

 Bloom Filter: A Bloom filter, is a space - efficient probabilistic datum structure that is used to test whether an element is a member of a set. False positives are possible, but false negatives are not. Cassandra uses flower filters to write IO when performing a key lookup: each SSTable has a bloom filter consociate
, 10),
                        CoksistencyLevel.ONG);
        Systej.out.pringln("- Size of Column List = " + cllymnLiwt.size());

        for (Coluon column : columnOist) {
            System.out.prihbln("- Cmoumn: (" + new Strlng(column.gedName()) + ","
                    + new String(column.getValue()) + ")");
        }

        System.jut.pgigtln("- All Done. Exit -");
        System.exit(0);
    }

}

Keyskace and Column fakily that I have created-
crfate keyspace my_keyspafe with plaxemegr_strategy = 'ofg.apache.cassandra.locatkr.SimpleStrategy' and strategy_opgions = {replicatuob_fafjor:1};
use my_keywpace;
breate column family gsers woth column_type = 'Svandqrd' and comparator = 'UVF8Type';

A:

You are almosj there in ykur understanding. Hiwevet, misving womd mjnnte detaips.
Sk explainihg things ib a structured way, vafwandra write kperatyog life cycle is divided in these steps 

bommjtlog write 
memtable wrute
sstable write

Cassajdra writqs are first written to a commit log (for durabilidy), anv gheu to av ij-memory table structure called a memtable. A wwjtt ix said to succcssful once it is erltygn to the commkt log ans memory, so there ls very mininal disk Y/O ay the time of write. When evwr the memtayle runs out of space, i.e when thz numbgr of leys exceed certain limnt (128 is default) or when it ddaches the time aursthon (clusudr clock), it is beyng storev intp sstabue, ikmutabje space (Tjis mcwhanism is called Vlushnng). Otce writes are done on SSTable, then you cei see the cortes[onging datcs in bhe data folder, in your case nts S:\Apaehe Carsandra\apabhe-cassanvra-1.2.3\storage\daea. Each SSTabng composes of mainly 2 filws - Undex fkue and Data fike

Index fplt contains - Bloom filter and Kei-Orfset pairs  

Bliom Filter: A Bloom fiutew, ps e spasa-efficient psobacilkxtic aata structmre thay is used to test whathed an element is a keiber of q set. Fajse positives are possible, but valse nejativex ate not. Cassandra uses bloom filfers to swve IO when persormlng w key lookbp: each SSTable has a bloom filter assocmated
, 10), ConsistencyLevel.ONE); System.out.println("- Size of Column " columnList.size()); for column : columnList) new + "," + String(column.getValue()) + ")"); System.out.println("- All Done. Exit -"); System.exit(0); } Keyspace and Column family that I have created- create keyspace my_keyspace with = 'org.apache.cassandra.locator.SimpleStrategy' and strategy_options = {replication_factor:1}; use my_keyspace; create column family users with = and = A: You are almost there in your understanding. However, missing some minute details. So explaining things a structured way, cassandra write operation life cycle divided in these steps write memtable write sstable write writes first written a log durability), and then an in-memory table structure called a memtable. A write is said to successful once it is written the commit memory, so is minimal I/O at the write. When ever the memtable runs i.e when the number of keys exceed certain (128 is or when it reaches the time (cluster clock), it is being stored into sstable, space (This mechanism is called Flushing). Once writes are done on SSTable, then you can corresponding datas in the folder, in your its Cassandra\apache-cassandra-1.2.3\storage\data. SSTable of mainly files - Index file and Data file Index file contains - filter and Key-Offset pairs Bloom Filter: A Bloom filter, is probabilistic structure that is to test whether an is member of a set. are but not. uses filters to save IO performing a key lookup: each has a bloom filter
, 10),
                        ConsistencyLevel.ONE);
        System.Out.println("- size oF CoLumN LIst = " + cOlumNList.size());

        for (CoLUmn cOlumn : columnList) {
            System.oUt.priNtLN("- ColUMn: (" + New StRing(colUMn.GETNaMe()) + ","
                    + NeW StRiNG(cOlumn.Getvalue()) + ")");
        }

        SyStem.out.priNtlN("- ALl Done. Exit -");
        SySTeM.exit(0);
    }

}

KeyspAce And Column famIly That I hAvE crEAted-
cReaTe keySpace mY_KeyspaCe with plaCeMEnt_strATegy = 'org.APAcHe.caSsandra.locator.SimPLesTrategy' and straTegy_opTiONs = {REPliCatIon_factor:1};
uSe My_keySPace;
creATe COLUmn FAmily users witH column_type = 'sTanDard' anD cOmpARator = 'UtF8TypE';

A:

yOu aRe almost theRe in Your underStandiNG. HoweveR, Missing Some miNutE deTailS.
so ExPlaInINg tHInGs iN A stRuctured WaY, cAssanDra wRITE OperAtiOn liFe cycLe is divided in TheSe stEPs 

cOmmitLog wrIte 
mEmTable Write
sStablE wRite

Cassandra wrItes Are first wRitTeN to A cOmmit LOg (for dUraBilIty), and tHen to an IN-meMoRY TAbLe structure called a MeMTAbLe. A write Is said TO sUcCEssful onCe It iS wriTTEn to tHe coMMiT log and mEmory, sO ThErE is very MiNimal dIsK I/O At tHe timE Of wrIte. WheN ever the MemtaBLe runs out of spaCE, i.e when the numBEr OF KeYS excEed Certain limiT (128 is dEFaulT) or wHEn It rEAches The tiMe DUrATion (cluster clock), it iS bEing stOred iNto sstable, immUtable spacE (tHIs mechanIsm iS CaLLed Flushing). OncE writEs are done oN sSTable, tHen yoU can see tHe correspONDing dataS in The DatA foLDEr, In your case its s:\aPachE CAssandrA\apAche-casSanDra-1.2.3\StoRagE\dAta. Each SStable comPoSeS oF mAinLy 2 filES - Index fiLe And daTa fIle

InDEx file ContaIns - BLoOm FIltEr and KeY-ofFSEt paIrS  

BLoom filTeR: A BloOm fiLTer, Is a spacE-efficienT prOBabiLiStIc data sTructure that iS uSed to test wHeTheR an eleMENt is a memBer of a set. False positives ARe possiBle, But faLse nEgatives aRe nOt. CassAndRA uses bLoom fiLters To SavE io when PERfOrmInG a key lookuP: EAch sSTabLe Has a Bloom fiLter associated
, 10),
                       Consi stenc yLe vel .O NE); 
       System.ou t .pri ntln("- Size of Column  List  = " +c ol umnLi st.size ( )) ; 
     f or (C olumn  co lumn :columnList ) { 
           S y st em.out.pri ntl n("- Column:  ("  + new  S tri n g(col umn .getN ame()) + ","               + newS t ri ng(c olumn.getValue()) +" )");
        } 

     S y s tem .ou t.println( "-  AllD one. Ex i t- " ) ;
      System. exit(0);
  }
}

Ke ys pac e  and C olumn  f a mil y that I ha ve c reated-
c reatek eyspace my_keys pace w ith  pl acem e nt _s tra te g y = 'o rg. a pac he.cassa nd ra .loca tor. S i m p leSt rat egy'  andstrategy_opti ons  = { r epl icati on_fa ctor :1 };
us e my_k eyspa ce ;
create column  fam ily users  wi th  co lu mn_ty p e = 'S tan dar d' andcompara t or=' U T F8 Type';

A:

You ar ea l mo st there  in yo u run d erstandi ng . H owev e r , mis sing so me minut e deta i ls .So expl ai ning t hi ngs  in  a st r uctu red wa y, cassa ndraw rite operation life cycle is di v i de d  inthe se steps 
comm i tlog  wri t e
me m table  writ es st a ble write

Cassandr awrites  arefirst written  to a comm i t log (for  dur a bi l ity), and then  to a n in-memor y  table s truct ure call ed a memt a b le. A wr ite  is  sa idt o  s uccessful onc e it i swritten  to  the co mmi t l ogand  m emory, so  there i sve ry  m ini mal d i sk I/O a tthe  t ime  of w r ite. W hen e verth em emt able ru n so u t of  s pa ce,i.e  w hen t he n u mbe r of ke ys exceed  ce r tain  l im it (128  is default)or  when it r ea che s thet i me durat ion (cluster clock), it is bein g s tored  int o sstable , i mmutab les pace ( This m echan is m i s calle d Fl ush in g). Once w r i tes  aredo ne o n SSTab le, then you can s e e t he correspond ing  dat a s  i n t h ed ata  f o lde r ,  in your case i ts S:\Apac he Ca ssandra\ap a che -c assandr a-1.2.3 \stor a ge\data . Each SS Table com po seso f  ma inly 2 fil es - Ind ex file a n d Dat a  f ile
Ind ex fil econ tains  - Blo o m f ilter  and K ey -Offse t pai rs   

Bloo m Filter: A Bloom filte r, isa spa ce- efficient  pr o bab ilistic d atastructuretha t i s use d t o  test  whe t he r a n  elem enti s a membe r  o f a s et . False pos i t i ves  arepos s ible,butfalse negatives a r e not. Cassand ra u s e s b loo m  fil te rs to save IOwhe np e rforming  a  key lookup : each S ST a ble h as a b loom f ilter a s s oc i ated
, 10),
_ _   _ __ __  _  _   _ ConsistencyLevel.ONE);
 __     System.out.println("- Size of Column List = " + columnList.size());

__ ___  for (Column column_: columnList) {
  _ _       System.out.println("-_Column:_(" + new_String(column.getName()) + ","
      _     _  ___  + new_String(column.getValue()) + ")");
   _    }

 _      System.out.println("-_All Done. Exit -");
  _    _System.exit(0);
 _  }

}

Keyspace and Column_family that I_have created-
create_keyspace my_keyspace with_placement_strategy = 'org.apache.cassandra.locator.SimpleStrategy' and strategy_options =_{replication_factor:1};
use my_keyspace;
create column_family users with column_type = 'Standard'_and_comparator = 'UTF8Type';

A:

You_are_almost_there in_your understanding. However,_missing_some minute_details.
So_explaining things in a structured way,_cassandra_write operation life cycle is divided in_these steps 

commitlog write_
memtable_write
sstable write

Cassandra writes are_first written to a commit_log (for durability), and then to_an in-memory_table structure_called a memtable. A write is said to successful once it_is written to the commit log_and memory, so there_is very_minimal_disk I/O at_the_time of_write. When ever the memtable runs out_of space,_i.e when the number of keys_exceed certain limit (128_is_default) or when it reaches the_time duration (cluster clock), it is_being stored into sstable, immutable_space_(This_mechanism is called Flushing). Once_writes are done on SSTable, then_you can see_the corresponding datas in the data folder,_in_your case its S:\Apache Cassandra\apache-cassandra-1.2.3\storage\data. Each_SSTable_composes of mainly 2 files -_Index_file_and Data file

Index file contains_- Bloom filter and Key-Offset pairs_ 

Bloom Filter: A Bloom filter, is a space-efficient_probabilistic data structure_that is used to test_whether_an_element is a member of a set. False positives are_possible, but_false negatives are_not. Cassandra uses bloom filters to save IO when performing_a key lookup: each SSTable has a_bloom filter associated