Database Reference
In-Depth Information
Table 4. Dictionary columns for
DMDSM and VDMDSM
Table 5. DMDSM
Table 6. VD-
MDSM
Dict. Column 0
Keyd0 Va l ued0
d02
Vector Column
Key Value
v1 d01,d11,d21
v2 d02,d12,d22
v3 d03,d13,d23
v4 d04,d11,d22
v5 d05,d11,d22
v6 d06,d13,d21
(a) Vector column
Columnv0
Keyv0 Va l uev0
k2 d02
k3 d03
k5 d05
k4 d04
k6 d06
k1 d01
(a) Primary key columns
clustered on value
Columnk2
Key Va l ue
k1 d21
k2 d22
k3 d23
k4 d22
k5 d22
k6 d21
(b) Columns clustered on key
Columnk1
Key Va l ue
k1
Dict. Column 1
Keyd1 Va l ued1
d11
Dict. Column 2
Keyd2 Va l ued2
d23
137
d11
d03
173
k2
d12
20090327
Christian
d05
317
d12
20071201
d21
Jana
k3
d13
d04
371
d13
20010925
d22
Tobias
k4
d11
d06
713
k5
d11
d01
731
k6
d13
(a) Dictionary columns
in search criteria as shown in Section 4. Our results in Section 4 suggest that
if we do not have any space constraint and we do need access using non-key
attributes, this scheme is not appropriate.
Dictionary based Minimal DSM (DMDSM). To improve the performance
of MDSM, we introduced DMDSM, which stores the unique data for each col-
umn separately as the dictionary column. DMDSM is inspired from the concept
of the dictionary encoding scheme, which is frequently used as light-weight com-
pression technique in many column-oriented data management systems [1]. In
DMDSM, for each main column, values are the keys for the data from dictionary
column as depicted in Table 5. All dictionary columns are clustered on value. All
other concepts for the DMDSM are similar to MDSM. This scheme gives us the
provision to exploit our innovative concept of evolving hierarchically-organized
storage structures to its maximum potential for dictionary columns.
VectorizedDictionary basedMinimal DSM(VDMDSM). VDMDSM is an
extension of DMDSM, such that it stores the values (i.e., dictionary column keys)
for all columns together as the vector column, i.e., instead of saving each column
separately, it generates the vector of all attributes in the row and stores it as a value
for vector column as depicted in Table 6. Similar to DMDSM, VDMDSM provides
the opportunity to exploit the benefit of evolving hierarchically-organized storage
structures to their full potential for dictionary columns.
3.2 Column-Level Customization and Storage Structure Hierarchies
Once we select the appropriate storage model scheme from above-mentioned
schemes at the table-level, we move forward to customize the columns as ex-
plained next. At the column-level, we customize the storage structure for each
column. Each column is initially customized as either ordered read-optimized or
unordered write-optimized storage structure. For ordered read-optimized storage
structures, we store data in sorted order with respect to key or value, whereas
for unordered write-optimized storage structure, we store data according to in-
sertion order. In the above-mentioned schemes, dictionary columns are always
stored as ordered read-optimized storage structures.
 
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