The canonical string decode operation, Jdbc and hadb date and time operations – Sun Microsystems Sun StorageTek 5800 User Manual
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When converting a typed value to a string as the result of the getAsString operation on a
NameValueRecord
or a QueryResultSet operation
■
When parsing a literal value as described in
“Literals for 5800 System Data Types” on
to create a typed query value from a string representation of that value.
The Canonical String Decode Operation
The inverse of the canonical string encoding is used in the following places:
■
It is always allowed to store a string value into any metadata field, no matter what the type
of the field is. The actual data stored is the result of applying the canonical string decode
operation to the incoming string value.
■
On a virtual view lookup operation, the canonical string decode operation is used on the
supplied filename to derive the actual metadata values to look up, given their string
representations in the filename.
The decode operation is allowed to accept incoming string values that would never be a
legal output for an encode operation. Some examples of this include:
– decodeBinary of an odd number of hex digits. The convention is to left-justify the
supplied digits in the binary value. For example, the string "b0a" corresponds to the
binary literal [b0a0].
– decodeDate of a non-standard date format.
– A double value encoded with a non-canonical number of digits. For example,
.00145E20
instead of 1.45E17.
EXAMPLE 4–1
Virtual View Lookup Operation
If you take a value V and encode it into a string S, and then perform the canonical decode
operation on S to get a new value V’. Does V always equal V’? The answer is yes in most cases, but
not always.
What is actually guaranteed is the weaker statement that if encode(V) = S and if decode(S)=V’,
then encode(V’) is also equal to S.
JDBC and HADB Date and Time Operations
■
Use the 5800 system literal format for all the Date and Time operations, for example, {date
’12-31-2007’}
.
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The JDBC standard escape sequences for date ({d ’YYYY-mm-dd’}) and time ({t
’hh:mm:ss’}) literals are available. However, usage of JDBC format date and time literals
may produce inconsistent results. In particular, when JDBC format is used, the literal
format is interpreted as being relative to the local time zone, and the time zone usually
differs between a 5800 system cluster and client machine.
JDBC and HADB Date and Time Operations
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