... BOOST_STATIC_ASSERT_MSG was added in boost 1.46, while the internal
boost is still at version 1.44, so use BOOST_STATIC_ASSERT instead.
Change-Id: I14f8e48e31956b34a1a907cd2c4e454a5715889b
We do a "SELECT * FROM table" just to fetch the primary key columns;
so reuse the same XResultSet to fetch all columns.
Else, we immediately issue a "SELECT * FROM table WHERE
primary_key=current_value" to read the other columns, which is
wasteful and particularly silly.
Commit 1ae17f5b03cc14844fb600ca3573a96deb37ab3b already tried
to do that, but was essentially reverted piecewise because
it caused fdo#47520, fdo#48345, fdo#50372.
Commit c08067d6da94743d53217cbc26cffae00a22dc3a thought it did that,
but actually reverted commit 1ae17f5b03cc14844fb600ca3573a96deb37ab3b.
This implementation fetches the whole current row and caches it in memory;
only one row is cached: when the current row changes, the cache contains
the new current row.
This could be problematic (wrt to memory consumption) if the current
row is big (e.g. with BLOBs) and nobody is interested in the data
anyway (as would often be the case with BLOBs). Note that because of
our "SELECT *", the driver most probably has it in memory already
anyway, so we don't make the situation that much worse.
This could be incrementally improved with a heuristic of not
preemptively caching binary data (and also not LONGVARCHAR / TEXT /
MEMO / ...); a getFOO on these columns would issue a specific "SELECT
column FROM table WHERE primary_key=current_value" each time.
The *real* complete fix to all these issues would be to not do "SELECT
*" at all. Use "SELECT pkey_col1, pkey_col2, ..." when we are only
interested in the key columns. As to data, somehow figure out which
columns were ar interested in and "SELECT" only these (and maybe only
those with "small datatype"?). Interesting columns could be determined
by our caller (creator) as an argument to our constructor, or some
heuristic (no binary data, no "big" unbound data).
Also be extra smart and use *(m_aKeyIter) when getFOO is called
on a column included in it (and don't include it in any subsequent
SELECT).
However, there are several pitfalls.
One is buggy drivers that give use column names of columns that we
cannot fetch :-| Using "SELECT *" works around that because the driver
there *obviously* gives us only fetchable columns in the result.
Another one is the very restrictive nature of some database access
technologies. Take for example ODBC:
- Data can be fetched only *once* (with the SQLGetData interface;
bound columns offer a way around that, but that's viable only for
constant-length data, not variable-length data).
This could be addressed by an intelligent & lazy cache.
- Data must be fetched in increasing order of column number
(again, this is about SQLGetData).
This is a harder issue. The current solution has the nice advantage
of completely isolating the rest of LibO from these restrictions.
I don't currently see how to cleanly avoid (potentially
unnecessarily) caching column 4 if we are asked for column 3 then
column 5, just in case we are asked for column 4 later on, unless
we issue a specific "SELECT column4" later. But the latter would be
quite expensive in terms of app-to-database roudtripe times :-( and
thus creates another performance issue.
Change-Id: I999b3f8f0b8a215acb390ffefc839235346e8353
fixup of d4ae29a37873843c20fe7d5f5f071f8fb201fed9
after the call to m_pCacheSet->absolute_checked, the data *is* used,
so we cannot anymore exempt m_pCacheSet from giving correct data.
Change-Id: I7d3644ca08ce43cb030a80984605a1f8a8a64211
This avoids asking the driver for the same data twice.
This is particularly important for ODBC data sources, because when asking for (VAR)CHAR data the second time, one gets no data (and status SQL_NO_DATA) because of the "retrieve in parts" semantics of these datatypes.
Change-Id: I96f2df9927fda72ccf19f78ec5c561f5626c003f
Instead, try to do the least unreasonable thing:
Fetch a new row
If that fails because no new row to fetch, at least we are properly positioned after last row. Calling code may not expect that and get confused, but that is the best we can do.
Change-Id: Ib7248e99ae3deee8344e9386cac2c9440e8bccd8
a) merge them together and move it into comphelper
b) turn it into a POD rather than having vast amounts
of destructors registered into the cxa_atexit chain
Change-Id: I04d3b9d7804f8e233013c916df9d617a0f84f96a
37b5dce665a03d3404e6a710b82bef16d740d178 re-wrote a std::rotate call to cause
an "error: function requires a valid iterator range [__middle, __last)" abort
from debug-mode GCC libstdc++ during smoketest. Lionel should check whether
this fix is actually good -- at least, it causes "make check" to succeed again.
It makes no sense, because non-nullable columns can have NULL value.
E.g. in "foo LEFT JOIN bar ON condition", the non-nullable columns of "bar"
when it has no row matching "condition".
Even when we are about to insert/update a row, we should not put a
hard-coded value (that just happens to be the one constructed by the
C++ default constructor for that type) in non-nullable columns: there
is no guarantee that this value makes sense in that database's context.
The database may or may not have a default value set for that column.
If it has, we should leave it up to the database to set it automatically.
If it has not, an error *is* the right reaction.
Another place where this substitution does damage is when we refresh a
row. We use the values we have read from the primary key to select the
row again. So we should not mangle those, else the select returns no
row and we mistakingly think the row has been deleted.
