Closed cloudfirst closed 3 years ago
env:
Hint means that: I know what I am doing, do not change anything, just send my QUERY to that I hint. When we use hint,we usually 1.R-W split. 2.Call procedure
In your case, looks like you need to just send a query like this:
select doc_eid, doc_title from scopus_paper where asjc between 1100 and 1229 order by doc_eid limit 5;
If your table scopus_paper
not contains column asjc
, you can use JOIN or check your table structure.
that is the reason why I have to use hint instead of join. column asjc is not included in table scopus_paper for business reason.
then I try to use hint to see whether it can get the same result as the case that column asjc is included in table scopus_paper.
if hint means run query in specified node(s) and concatenate the result from each node, I guess whether it is possible to add a new feature that will run sql type hint that route to multiple datanodes and process the result from each datanode as what ordinary SQL statement without hint does.
that is the reason why I have to use hint instead of join. column asjc is not included in table scopus_paper for business reason.
then I try to use hint to see whether it can get the same result as the case that column asjc is included in table scopus_paper.
if hint means run query in specified node(s) and concatenate the result from each node, I guess whether it is possible to add a new feature that will run sql type hint that route to multiple datanodes and process the result from each datanode as what ordinary SQL statement without hint does.
not sure whether it is a bug or not.
========================================================== mysql> explain select 1 from sid_asjc_re where asjc between 1100 and 1199; +---------------+----------+------------------------------------------------------------+ | SHARDING_NODE | TYPE | SQL/REF | +---------------+----------+------------------------------------------------------------+ | dn2 | BASE SQL | select 1 from sid_asjc_re where asjc between 1100 and 1199 | +---------------+----------+------------------------------------------------------------+
mysql> explain select 1 from sid_asjc_re where asjc between 1200 and 1299; +---------------+----------+------------------------------------------------------------+ | SHARDING_NODE | TYPE | SQL/REF | +---------------+----------+------------------------------------------------------------+ | dn3 | BASE SQL | select 1 from sid_asjc_re where asjc between 1200 and 1299 | +---------------+----------+------------------------------------------------------------+ 1 row in set (0.01 sec)
mysql> explain select 1 from sid_asjc_re where asjc between 1100 and 1229; +---------------+----------+------------------------------------------------------------+ | SHARDING_NODE | TYPE | SQL/REF | +---------------+----------+------------------------------------------------------------+ | dn2 | BASE SQL | select 1 from sid_asjc_re where asjc between 1100 and 1229 | | dn3 | BASE SQL | select 1 from sid_asjc_re where asjc between 1100 and 1229 | +---------------+----------+------------------------------------------------------------+
mysql> /!dble:sql=select 1 from sid_asjc_re where asjc between 1100 and 1199/ select doc_eid, doc_title from scopus_paper order by doc_eid limit 5; +---------+-----------------------------------------------------------------------------------------------+ | doc_eid | doc_title | +---------+-----------------------------------------------------------------------------------------------+ | 0 | 0 | | 110 | Symmetry of quantum phase space in a degenerate Hamiltonian system | | 227 | Lithography of 180nm design rule for 1Gbit DRAM | | 523 | Boundary subspaces for the finite element method with Lagrange multipliers | | 787 | A lagrangian method for calculating the dynamics of an incompressible fluid with free surface | +---------+-----------------------------------------------------------------------------------------------+ 5 rows in set (0.00 sec)
mysql> /!dble:sql=select 1 from sid_asjc_re where asjc between 1200 and 1299/ select doc_eid, doc_title from scopus_paper order by doc_eid limit 5; +---------+--------------------------------------------------------------------------------------------------------------+ | doc_eid | doc_title | +---------+--------------------------------------------------------------------------------------------------------------+ | 0 | 0 | | 649 | Automorphismengruppen von lokalkompakten zusammenh�ngenden Quasik�rpern und Translationsebenen | | 1074 | L-shell x-ray intensity ratios for au and pb at excitation energies 36.82, 43.95, 48.60, 50.20 and 53.50 kev | | 1789 | Object-Oriented Simulator Design For an Automated High-Speed Modular Placement Machine Family | | 1880 | Jump discontinuities of semilinear, strictly hyperbolic systems in two variables: Creation and propagation | +---------+--------------------------------------------------------------------------------------------------------------+ 5 rows in set (0.00 sec)
mysql> /!dble:sql=select 1 from sid_asjc_re where asjc between 1100 and 1229/ select doc_eid, doc_title from scopus_paper order by doc_eid limit 5; +---------+--------------------------------------------------------------------------------------------------------------+ | doc_eid | doc_title | +---------+--------------------------------------------------------------------------------------------------------------+ | 0 | 0 | | 110 | Symmetry of quantum phase space in a degenerate Hamiltonian system | | 227 | Lithography of 180nm design rule for 1Gbit DRAM | | 523 | Boundary subspaces for the finite element method with Lagrange multipliers | | 787 | A lagrangian method for calculating the dynamics of an incompressible fluid with free surface | | 0 | 0 | | 649 | Automorphismengruppen von lokalkompakten zusammenh�ngenden Quasik�rpern und Translationsebenen | | 1074 | L-shell x-ray intensity ratios for au and pb at excitation energies 36.82, 43.95, 48.60, 50.20 and 53.50 kev | | 1789 | Object-Oriented Simulator Design For an Automated High-Speed Modular Placement Machine Family | | 1880 | Jump discontinuities of semilinear, strictly hyperbolic systems in two variables: Creation and propagation | +---------+--------------------------------------------------------------------------------------------------------------+
what I expected is that : the last SQL statement will return the result that is REALLY ordered by doc_eid.