Joe Celko's Trees and Hierarchies in SQL for Smarties 2004
DOI: 10.1016/b978-155860920-4/50002-7
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Graphs, Trees, and Hierarchies

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Cited by 18 publications
(4 citation statements)
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“…Retrieval of ancestor and descendent taxa to arbitrary depth is supported by secondary indexing according to a modified preorder tree traversal algorithm [49]. Two sources (Tropicos, equivalent to the APG III classification [50], and NCBI taxonomy) serve as alternative family classifications; genera, species and infraspecific taxa from all sources are joined to these families by genus.…”
Section: Methodsmentioning
confidence: 99%
“…Retrieval of ancestor and descendent taxa to arbitrary depth is supported by secondary indexing according to a modified preorder tree traversal algorithm [49]. Two sources (Tropicos, equivalent to the APG III classification [50], and NCBI taxonomy) serve as alternative family classifications; genera, species and infraspecific taxa from all sources are joined to these families by genus.…”
Section: Methodsmentioning
confidence: 99%
“…The search engine is built on top of MySQL, an open-source relational database management system (RDBMS) [16]. PhyloFinder stores the phylogenetic trees, which in our test implementation are from TreeBASE [12,13], and the NCBI taxonomy tree [11] in MySQL using a slight modification [17] of nested-set representation [18,19]. Under this scheme, each node x of a given tree is represented by an interval [ N x , R x ], where N x , called the NodeID of x , is an integer defined by a preorder walk of the tree [20], and R x is the largest NodeID of a descendant of x (see Figure 5).…”
Section: Methodsmentioning
confidence: 99%
“…In order to reach a compromise between simplicity and flexibility, the authors chose a star-like databaseschematorepresentthemathematicalmodel,asshowninFigure3.Noticethegivenschema isneitherastarschemanoranERschema:itisahybridrepresentation.Duringtheinitialstageof theproject,itwasastar-schema,becauseitprovidesabasicschemathatcouldbegrownwithnew cubedimensions,dependingonadditionalinformationgivenbyusers'requirements.Butontheother hand,unfortunately,therecursiveparsertreestructurecouldnotberepresentedasapurestarschema, because it required a recursive node entity (Karwin, 2010;Celko, 2004). Therefore, introducing many-to-many(M:N)relationshipsintothestarschemathatoriginallyhadonlyone-to-many(1:N) relationshipswasnecessary.However,theauthorsmadeanefforttomaketheschemaassimilaras possibletoanactualstar-schemainordertoeasilyaddnewdimensionstothemodel,whichwould allowstoringusefulinformationabouttheequations(e.g.,dateofinsertion,experiment,nameof theexperimenter,etc).Forinstance,eachequationcanbelinkedtotheexperimenterwhoaddedthe equations.Theexperimenterhaspersonalinformationattributes(id,name,position,etc),butsuch personisalsopartofateam,whichispartofadepartment.Therefore,theexperimenterdimension hasthefollowinghierarchy:department<team<experimenter.Thenthestar-likeschemagives theopportunitytoperformaggregationoperationssuchasRoll-UporDrill-Down,inordertogroup equationsthatbelongstothesameexperimenter,thesameteam,orthesamedepartment.Similarly, addingthedateofinsertionoftheequationsinducesanadditionaltimedimension.Thenequations canbeaggregatedbymonth,yearoratimerange,whichcanhelptrackingthelaboratoryactivity.…”
Section: From Binary Parser Tree To Er Modelmentioning
confidence: 99%