When Karl pro-tested that local Nazis had arrested young workers in the neigh-borhood and seized a trade union building, his father retorted indialect, “Ordnung mot sein,” “You have to have order.”

Socialists around the worldhad celebrated May Day as a festival of labor since the 1880s; butin Germany they had failed to get the official recognition the Nazisnow offered. So strong were the hopes for national unity that theGerman Free Trade Unions welcomed the Nazi gesture and encour-aged members to participate in the celebrations.

the stunning media spectacle of thespeeches and celebrations of 1 May also contrasted with 2 May,when stormtroopers sealed off and took over the operations of thesocialist Free Trade Unions and incorporated them into what be-came the German Labor Front, an integral part of the National So-cialist apparatus.

The construction of the firstconcentration camps to media fanfare in March 1933, and therapid migration of the shorthand kz, for Konzentrationslager, intoordinary speech, left the public well aware that Nazis recognizedonly friends or foes;

the Nazis recognized only Volkskameraden, people’s com-rades, and Volksfeinde, enemies of the people, whom they sub-jected to deliberate and refined cruelties in a “willful transgressionof norms.

The state of permanent emer-gency declared by the National Socialists helps explain the tremen-dous efforts that they and their followers made to reconstruct thecollective body and the satisfaction they took in images of unityand solidarity. It also helps explain the violent exclusions they ac-cepted as part of the rebuilding process.

National Socialism offered acomprehensive vision of renewal, which many Germans found ap-pealing, but they combined it with the alarming specter of nationaldisintegration.

. It was the experience of conversion, which left peoplelike Dürkefälden and Ebermayer isolated, that was new and pro-vided the Third Reich with legitimacy and energy.

He repeatedly described Ger-many as a nation that had come home to itself. While Erich hatedthe Nazis, he loved the Third Reich.

the desire to be part ofnational unity was so strong that it pulled even an anti-Nazi such asErich into the new political community

“he doesn’t want to take part in any waragain,” Karl reported; “he has had enough.”

the prospect of a new war, a topic Germanfamilies discussed frequently in the years after 1933

restricting their rep-resentation in the professions to their proportion in the population:“that is one percent.” Moreover, she explained, “Jews want to rule,not serve.” The proof: “have you ever heard of a Jewish maid or aJewish laundry woman?”

In the national broadcast, selected party members spoke out thescripted reactions of “ordinary citizens,” who, appearing from allwalks of life, expressed support for Hitler.

The strong presence of the police,who tended to sympathize with the National Socialists, restrictedthe mobility of opponents, while Nazi toughs broke into SocialDemocratic or trade union offices and Nazi officials banned so-cialist newspapers.

Held on 21 March 1933 in Potsdam’s Garnisonkirche, whereFrederick the Great lay buried, the Day of Potsdam aligned Hit-ler with revered Prussian traditions, the Hohenzollern dynasty andthe founding of the German Reich some sixty years earlier, andthe heroic sacrifices of the Great War, represented by the “hero ofTannenberg,” President Paul von Hindenburg,

“I was overcomewith a burning desire to belong to these people for whom it was amatter of life and death.” Maschmann herself was drawn to the“socialist tendency” of the Nazi movement, the idea of the people’scommunity,

the “August Days” of 1914, when thou-sands of Germans rallied in the streets to support the national causein time of war, revealed extraordinary emotional investment in thepromise of national unity.

The enduring popularity of the Nazis rested on the idea of theVolksgemeinschaft, or people’s community.

the officially organized boycott of Jewish businesses on 1April 1933 required a more considered answer. Elisabeth beganwith a concession, contrasting the “happiness” of the world-histor-ical events taking place in Germany with her “sympathy” for “thefate of the individual.”

ample, “is now a Nazi because of his job, but only for show.”Peine’s barber was in the SA, but Karl thought for “professionalreasons” only.

what he saw was an increas-ingly Nazified community in which neighbors now took notice ofKarl’s behavior and club members adjusted their own. What Karlwas resisting as he stood alongside his wife was the pressure to con-form, if only for the sake of appearances.

sincediscussions about Jewish suffering frequently switched to the sub-ject of German suffering: “Versailles” had taken the “opportunitiesfor life” away from Germans, who were now “completely under-standably” fighting back on behalf of their “own sons.”

by far the most illuminating to me is the idea that mental causation works from virtual futures towards the past 00:33:17 whereas physical causation works from the past towards the future and these two streams of causation sort of overlap in the present

collectively solve a local environ-mental problem

Sweden Poised to Miss the Long-Term Climate Target It Pioneered

structure

There is a format for recording information based around connections called a concept map. Concept maps are spatial representations of knowledge, in which a concept is represented as a circle (node) and a connection/statement is represented as a line connecting two circles (edge). But concept mapping is limited in its current forms. Making a concept map is messy and often when handwritten. It is very difficult to have enough foresight in making a concept map as to prevent lines (representing edges) from crossing each other all over the page. Moreover, though concept maps have advantages over bullet points and other linear note-taking techniques in their ability to store and model nonlinear knowledge, existing software that is meant for creating concept maps is meant more for presentational purposes, e.g., creating a diagram that might be included in a report, than for recording notes in real time and understanding, organizing, or manipulating notes.

It is quite “normal,” and human, to not enjoy making mistakes! That is why we often feel embarrassed, deny their existence, and/or blame others for our errors. We believe that the best way is to admit your mistakes, learn from them and take corrective action. After all, a mistake is a mistake – no more, no less.

Chris, Chris... concepts and propositions are not nebulous dictionary definitions unless you're joining the Frankfurt School :) :).Click here to get some clarity about these basic terms as applied to learning: https://cmap.ihmc.us/docs/concept.phpAbout systems and emergence, I prefer Mario Bunge's book: https://www.amazon.com/Emergence-Convergence-Qualitative-Knowledge-Philosophy/dp/1442628219Irony? No way. You are always bringing new information about the historical roots of Zettelkasten. Keep doing that, please! Thanks!

First, I am a big fan of Chris’ posts. He is our best historian. Second, I did not challenge his ideas but asked for clarification about some terms which I believe are of general interest. Chris is well-positioned to answer my questions. Third, statistical mechanics is more about microscopic systems that do not evolve. As we know, ideas (from concepts to theories) evolve and generally emerge from previous ideas. Emergence is the key concept here. I suggested Phenomics as a potential metaphor because it represents well the emergence of some systems (phenotypes) from pre-existing ones (genotypes).

Prof. Joseph Novak (Cornell) developed conceptual maps based on David Ausubel's subsumption (aka meaningful learning) theory and Piaget's concept of conceptual schemes. Conceptual maps have been proven successful across all levels of education worldwide (check Google Scholar).

Zettelkasten can be described as a collection of conceptual maps in a written format.

Sustainability is inadequate as a concept

And yes: that’s certainly how a lot of capitalist cultures think about time — as something that can be wasted or optimized. It’s often predicated on the idea that you should be focused on doing one thing, and one thing only, very efficiently: time is money, etc. etc. But that itself, sometimes referred to as a “monochronic” understanding of time, is no more or less “natural” than other ways of conceiving of time, like “polychronic” culture, which understands time as dynamic, flexible, and filled with several tasks at once, each of which will take the time that they need. Monochronic cultures may be more “efficient” in their use of time, but in their treatment of time as a commodity, they lose the richness that comes with allowing tasks, conversations, and interactions to move forward at a more natural and sustainable pace.

A workspace is a collection of modules on disk that are used as the main modules when running minimal version selection (MVS).

If you give a title to your notes, "claim notes" are simply notes with a verb. They invite you to say: "Prove it!" - "The positive impact of PKM" (not a claim) - "PKM has a positive impact in improving writer's block" (claim) A small change with positive mindset consequences

fictional ecologies

the problem with docker builds is the made-up concept of "context". Dockerfiles are not sufficient to define a build, unless they are placed under a strategic directory (aka context), i.e. "/" as an extreme, so you can access any path (note that that's not the right thing to do in a sane project either..., plus it makes docker builds very slow because docker scans the entire context at start).

let me make a few comments if i may about time from nagarjuna's perspective there is no 01:25:52 time i don't think i can be more brief and how does he support that he says well when you're in the present moment there's no past and there's no future 01:26:06 if you dissect the present moment even to a more granular present moment some of that's going to be passed some of that's going to be yet to come and then you have even a finer more 01:26:18 granular present moment if you keep going on with that granularity you end up having no time you have no past no future and no presence so that's kind of in a nutshell some of the arguments or 01:26:32 logic that knock arjuna nagarjuna uses to establish no time now of course what he means is there's no absolute time there's no time on a some there's no essence of time um there is you know 01:26:46 time from the perspective of of of conventionality um cause and effect is reciprocal so when we have a cause we have an effect or we know there's 01:26:59 going to be an effect but also from the point of view of the effect the result we know that there must have been a cause so this reciprocality is something unique to the highest 01:27:10 school of prasannika majamaka uh within the fourth highest school of majamaca i just wanted to mention that to to round out one of our previous discussions

suppose when you needed to make a permanent edit to the style sheet on your homepage, you opened up the CSS viewer, made the edit, and the result persists—not just in your browser, but by changing the very style sheet itself

I think they are a significant pedagogical idea because they help people understand how these sorts of thing work.

To test whether these distributed representations of meaning are neurally plausible, a number of studies have attempted to learn a mapping between particular semantic dimensions and patterns of brain activation

Concept car projects explore the boundaries of current technologies or showcase what new designs and ideas enable. They are necessary to push the field forward, but usually too rough or incomplete for the rest of the world to depend on.

Since ROX is a passive fluorescent dye, the main reason it is used in qPCR is for signal normalisation. By normalising the fluorescent signal, this can reduce the variability between technical replicates.

POC vs MVP: What to Choose to Build a Great ProductDmitryCEOMVPHomeBlogEntrepreneurshipPOC vs MVP: What to Choose to Build a Great ProductPublishedNov 10, 2021UpdatedNov 11, 202115 min readWhen it comes to creating a new product or implementing a new feature, you need to test it first. The best way to do so is to check your idea with the appropriate steps. There are several software product stages: PoC, prototype, MVP, etc. What is the difference between proof of concept vs. MVP? Why are these stages essential? When should you build a Minimum Viable Product? This article focuses on two fundamental approaches that help test your idea quickly and create a successful solution.

But it is always important to remember that those are not language concepts. Those are community concepts that only exist in our heads and in the names of some library methods.

Note: when I wrote above that "there is no such thing as X", what I meant was that "there is no such thing as X in the Ruby language". That does not mean that those concepts don't exist in the Ruby community.

Right now, we are building a concept proofing prototype using Anycable.

A Gaussian process is a probability distribution over possible functions.

Micromachines always focused on local multiplayer, and the fun their eccentric races of small toy vehicles competing on tracks made with everyday objects; and all that is present.

There's probably a thousand different directions you can go, but there just needs to be some kind of deeper hook to make this a full-fledged game.

The question, 'What is library and information science?' does not elicit responses of the same internal conceptual coherence as similar inquiries as to the nature of other fields, e.g., 'What is chemistry?', 'What is economics?', 'What is medicine?' Each of those fields, though broad in scope, has clear ties to basic concerns of their field. [...] Neither LIS theory nor practice is perceived to be monolithic nor unified by a common literature or set of professional skills. Occasionally, LIS scholars (many of whom do not self-identify as members of an interreading LIS community, or prefer names other than LIS), attempt, but are unable, to find core concepts in common

One day last August 2018, I stumbled upon an online petition that sparked my curiosity - We Want Serverless Ruby. At that time, none of the major cloud providers had first-class support for Ruby in their serverless products. There were ~1400 devs signing that petition, and I wondered if there was something about Ruby that made it unsuitable for FaaS. I decided to roll the sleeves and start building what would be the first PoC of faastRuby.

Players try to build a village together. As the game goes on each player secretly chooses whether they want to go for a coop victory or a single-player win.

 Vision-based combat. The success of a ninja action is solely based on guards’ vision.

Examples of different ways of defining forms

For the usage in society, see Second-class citizen.

In programming language design, a first-class citizen (also type, object, entity, or value) in a given programming language is an entity which supports all the operations generally available to other entities. These operations typically include being passed as an argument, returned from a function, modified, and assigned to a variable.

In computer science, a programming language is said to have first-class functions if it treats functions as first-class citizens.

Teacher Preparation

The key phrase here is “children of a grid container.” The specification defines the creation of a grid on the parent element, which child items can be positioned into. It doesn’t define any styling of that grid, not even going as far as to implement something like the column-rule property we have in Multi-column Layout. We style the child items, and not the grid itself, which leaves us needing to have an element of some sort to apply that style to.

去濕氣。

La perspective "technocentrée" selon laquelle les outils technologiques déterminent seuls les processus cognitifs humains

C'est par la théorie socioculturelle, issue des travaux de Vygotski, que nous devons commencer

L’affordance se comprend comme

This plugin was designed as a proof-of-concept for a feature that's destined for Rails 4. It has only been tested on Rails 3.2+, but may work on earlier versions as well.

Self-concept also differs from self-esteem: self-concept is a cognitive or descriptive component of one's self (e.g. "I am a fast runner"), while self-esteem is evaluative and opinionated (e.g. "I feel good about being a fast runner").

Self-concept is distinguishable from self-awareness, which refers to the extent to which self-knowledge is defined, consistent, and currently applicable to one's attitudes and dispositions.

Subgroups of the computer underground with different attitudes and motives use different terms to demarcate themselves from each other. These classifications are also used to exclude specific groups with whom they do not agree.

many of students would be far better off earning a vocational degree at a low-cost community college, or using that community college as a spring-board into a more affordable four-year degree, to be paid for with a combination of student loans and (ideally) parental tuition assistance.

In these two languages, the "Function is a first-class citizen, which allows for aggregation of behaviors outside of the class.

We can treat navigation as a first-class concept, even encoding state transitions in links.

lead nurturing

Product-oriented content also comes in handy — product overviews (40%), case studies (34%), and landing pages (31%) proved to be effective in generating leads.

A content marketing funnel is a system that helps a brand to attract potential clients and guide them through their journey from the first interaction to conversion to a paying customer. 

Now, when the user interacts with the keypad, the value of pin in the parent component is immediately updated.

Architecture is the materialization of a concept

With this second scheme, the DBMS stores the physical addressof versions in the index entries. This approach is only applicablefor append-only storage, since the DBMS stores the versions in thesame table and therefore all of the indexes can point to them. Whenupdating any tuple in a table, the DBMS inserts the newly createdversion into all the secondary indexes. In this manner, the DBMScan search for a tuple from a secondary index without comparingthe secondary key with all of the indexed versions. Several MVCCDBMSs, including MemSQL and Hekaton, employ this scheme

The main idea of using logical pointers is that the DBMS usesa fixed identifier that does not change for each tuple in its indexentry. Then, as shown in Fig. 5a, the DBMS uses an indirectionlayer that maps a tuple’s identifier to the HEAD of its version chain.This avoids the problem of having to update all of a table’s indexesto point to a new physical location whenever a tuple is modifiedHEADINDEXVERSION CHAINSHEADINDIRECTION(a)Logical PointersHEADINDEXVERSION CHAINSHEAD(b)Physical PointersFigure 5: Index Management– The two ways to map keys to tuples in aMVCC are to use logical pointers with an indirection layer to the versionchain HEAD or to use physical pointers that point to an exact version.(even if the indexed attributes were not changed). Only the mappingentry needs to change each time. But since the index does not pointto the exact version, the DBMS traverses the version chain fromthe HEAD to find the visible version. This approach is compatiblewith any version storage scheme. As we now discuss, there are twoimplementation choices for this mapping

Tuple Id (TupleId):One drawback of thePKeypointers is thatthe database’s storage overhead increases as the size of a tuple’sprimary key increases, since each secondary index has an entirecopy of it. In addition to this, since most DBMSs use an order-preserving data structure for its primary key indexes, the cost ofperforming the additional look-up depends on the number of entries.An alternative is to use a unique 64-bit tuple identifier instead ofthe primary key and a separate latch-free hash table to maintain themapping information to the tuple’s version chain HEAD.

Primary Key (PKey):With this, the identifier is the same as thecorresponding tuple’s primary key. When the DBMS retrieves anentry from a secondary index, it performs another look-up in thetable’s primary key index to locate the version chain HEAD. If asecondary index’s attributes overlap with the primary key, then theDBMS does not have to store the entire primary key in each entry.

Primary key indexes always point to the current version of a tuple.But how often the DBMS updates a primary key index depends onwhether or not its version storage scheme creates new versions whena tuple is updated. For example, a primary key index in the deltascheme always points to the master version for a tuple in the maintable, thus the index does not need to be updated. For append-only,it depends on the version chain ordering:N2Orequires the DBMSto update the primary key index every time a new version is created.If a tuple’s primary key is modified, then the DBMS applies this tothe index as aDELETEfollowed by anINSERT

We define anindex entryas a key/value pair, where thekeyis atuple’s indexed attribute(s) and thevalueis a pointer to that tuple.The DBMS follows this pointer to a tuple’s version chain and thenscans the chain to locate the version that is visible for a transaction.The DBMS will never incur a false negative from an index, but itmay get false positive matches because the index can point to aversion for a key that may not be visible to a particular transaction.

Since MVCC creates new versions when transactions updatetuples, the system will run out of space unless it reclaims the versionsthat are no longer needed.

In this GC mechanism, the DBMS reclaims storage space attransaction-level granularity. It is compatible with all of the versionstorage schemes. The DBMS considers a transaction as expiredwhen the versions that it generated are not visible to any activetransaction. After an epoch ends, all of the versions that weregenerated by the transactions belonging to that epoch can be safely

Cooperative Cleaning (COOP):When executing a transaction,the DBMS traverses the version chain to locate the visible version.During this traversal, it identifies the expired versions and recordsthem in a global data structure. This approach scales well as theGC threads no longer needs to detect expired versions, but it onlyworks for theO2Nappend-only storage. One additional challengeis that if transactions do not traverse a version chain for a particulartuple, then the system will never remove its expired versions. Thisproblem is called “dusty corners” in Hekaton [16]. The DBMSovercomes this by periodically performing a complete GC pass witha separate thread like inVAC.

Background Vacuuming (VAC):The DBMS uses backgroundthreads that periodically scan the database for expired versions. Asshown in Table 1, this is the most common approach in MVCCDBMSs as it is easier to implement and works with all version stor-age schemes. But this mechanism does not scale for large databases,especially with a small number of GC threads. A more scalableapproach is where transactions register the invalidated versions ina latch-free data structure [27]. The GC threads then reclaim theseexpired versions using the epoch-based scheme described above.Another optimization is where the DBMS maintains a bitmap ofdirty blocks so that the vacuum threads do not examine blocks thatwere not modified since the last GC pass

There are two GC implementations for a MVCC that differ onhow the DBMS looks for expired versions. The first approachistuple-levelGC wherein the DBMS examines the visibility ofindividual tuples. The second istransaction-levelGC that checkswhether any version created by a finished transaction is visible

The DBMS registers each newtransaction into the active epoch and increments this counter. Whena transaction finishes, the DBMS removes it from its epoch (whichmay no longer be the current active one) and decrements this counter.If a non-active epoch’s counter reaches zero and all of the previousepochs also do not contain active transactions, then it is safe for theDBMS to reclaim expired versions that were updated in this epoch

An in-memory DBMS can avoid this problem with coarse-grainedepoch-basedmemory management that tracks the versions createdby transactions [44]. There is always one active epoch and an FIFOqueue of prior epochs

The GC process is divided into three steps: (1) detect expiredversions, (2) unlink those versions from their associated chains andindexes, and (3) reclaim their storage space. The DBMS considers aversion as expired if it is either an invalid version (i.e., created byan aborted transaction) or it is not visible to any active transaction.For the latter, the DBMS checks whether a version’send-tsisless than theTidof all active transactions. The DBMS maintainsa centralized data structure to track this information, but this is ascalability bottleneck in a multi-core system

all of the tuple versions for a table are storedin the same storage space. This approach is used in Postgres, aswell as in-memory DBMSs like Hekaton, NuoDB, and MemSQL.To update an existing tuple, the DBMS first acquires an empty slotfrom the table for the new tuple version. It then copies the contentof the current version to the new version. Finally, it applies themodifications to the tuple in the newly allocated version slot.

With this last scheme, the DBMS maintains the master versionsof tuples in the main table and a sequence ofdelta versionsin aseparatedelta storage. This storage is referred to as therollbacksegmentin MySQL and Oracle, and is also used in HyPer. Mostexisting DBMSs store the current version of a tuple in the main table.To update an existing tuple, the DBMS acquires a continuous spacefrom the delta storage for creating a new delta version.

the older versions are stored in a separate table. TheDBMS maintain amasterversion of each tuple in the main table andmultiple versions of the same tuple in a separate time-travel table.In some DBMSs, like SQL Server, the master version is the currentversion of the tuple. Other systems, like SAP HANA, store theoldest version of a tuple as the master version to provide snapshotisolation

Newest-to-Oldest (N2O):The alternative is to store the newestversion of the tuple as the version chain’s HEAD (see Fig. 3b). Sincemost transactions access the latest version of a tuple, the DBMS doesnot have to traverse the chain. The downside, however, is that thechain’s HEAD changes whenever a tuple is modified. The DBMSthen updates all of the table’s indexes (both primary and secondary)to point to the new version. As we discuss in Sect. 6.1, one canavoid this problem through an indirection layer that provides a singlelocation that maps the tuple’s latest version to physical address. Withthis setup, the indexes point to tuples’ mapping entry instead of theirphysical locations. This works well for tables with many secondaryindexes but increases the storage overhead

The key decision with the append-only scheme is how the DBMSorders the tuples’ version chains. Since it is not possible to maintaina latch-free doubly linked list, the version chain only points in onedirection. This ordering has implications on how often the DBMSupdates indexes whenever transactions modify tuples.Oldest-to-Newest (O2N):With this ordering, the chain’s HEADis the oldest extant version of a tuple (see Fig. 3a). This versionmight not be visible to any active transaction but the DBMS has yetto reclaim it. The advantage ofO2Nis that the DBMS need notupdate the indexes to point to a newer version of the tuple wheneverit is modified. But the DBMS potentially traverses a long versionchain to find the latest version during query processing. This is slowbecause of pointer chasing and it pollutes CPU caches by readingunneeded versions. Thus, achieving good performance withO2Nishighly dependent on the system’s ability to prune old versions

thechain’s HEAD is either the newest or oldest version

A transaction can commit only when all ofthe transactions that it depends on have committed.

Atransaction is allowed to commit only when its dependency counteris zero, whereupon the DBMS traverses its dependency list anddecrements the counters for all the transactions that are waitingfor it to finish.

The serial safety net (SSN) is a newer certifier-based proto-col [45]. Unlike withSSI, which is only applicable to snapshotisolation,SSNworks with any isolation level that is at least as strongasREAD COMMITTED. It also uses a more more precise anomaly de-tection mechanism that reduces the number of unnecessary aborts.SSNencodes the transaction dependency information into meta-data fields and validates a transactionT’s consistency by computinga low watermark that summarizes “dangerous” transactions thatcommitted before theTbut must be serialized afterT[45]. Re-ducing the number of false aborts makesSSNmore amenable toworkloads with read-only or read-mostly transactions

the DBMS maintains a serialization graphfor detecting and removing “dangerous structures” formed by con-current transactions

When a transaction commits, the DBMSassigns it a unique timestamp (Tcommit) that is used to update thebegin-tsfield for the versions created by that transaction and thenreleases all of the transaction’s locks.

Similarly, atransaction is allowed to update a versionBxonly if bothread-cntandtxn-idare set to zero

To perform a read operation on a tupleA, the DBMS searches fora visible version by comparing a transaction’sTidwith the tuples’begin-tsfield. If it finds a valid version, then the DBMS incre-ments that tuple’sread-cntfield if itstxn-idfield is equal to zero(meaning that no other transaction holds the write lock)

The tuple’swrite lockis thetxn-idfield. For theread lock, the DBMS usesaread-cntfield to count the number of active transactions thathave read the tuple. Although it is not necessary, the DBMS canpacktxn-idandread-cntinto contiguous 64-bit word so that theDBMS can use a single CaS to update them at the same time

This protocol uses the two-phase locking (2PL) method [11] toguarantee the transaction serializability. Every transaction acquiresthe proper lock on the current version of logical tuple before it isallowed to read or modify it.

But atransaction cannot read a new version until the other transaction thatcreated it commits. A transaction that reads an outdated version willonly find out that it should abort in the validation phase

If the transaction passes these checks, it then enters thewrite phasewhere the DBMS installs all the new versions and setstheirbegin-tstoTcommitandend-tstoINF

When a transaction instructs the DBMS that it wants to commit,it then enters thevalidation phase. First, the DBMS assigns thetransaction another timestamp (Tcommit) to determine the serializationorder of transactions. The DBMS then determines whether the tuplesin the transaction’s read set was updated by a transaction that alreadycommitted.

TheMVOCCprotocol splits a transaction into three phases.When the transaction starts, it is in theread phase. This is where thetransaction invokes read and update operations on the database. LikeMVTO, to perform a read operation on a tupleA, the DBMS firstsearches for a visible versionAxbased onbegin-tsandend-tsfields.Tis allowed to update versionAxif its write lock is not ac-quired. In a multi-version setting, if the transaction updates versionBx, then the DBMS creates versionBx+1with itstxn-idset toTid

The motivation behind OCCis that the DBMS assumes that transactions are unlikely to conflict,and thus a transaction does not have to acquire locks on tuples whenit reads or updates them.

WithMVTO, a transaction always updates the latest version ofa tuple. TransactionTcreates a new versionBx+1if (1) no activetransaction holdsBx’s write lock and (2)Tidis larger thanBx’sread-tsfield. If these conditions are satisfied, then the DBMScreates a new versionBx+1and sets itstxn-idtoTid. WhenTcommits, the DBMS setsBx+1’sbegin-tsandend-tsfields toTidandINF(respectively), andBx’send-tsfield toTid

Upon readingAx, the DBMS setsAx’sread-tsfield toTidif its current value is less thanTid. Otherwise, the transaction readsan older version without updating this field

When transactionTinvokes a read operation on logical tupleA,the DBMS searches for a physical version whereTidis in betweenthe range of thebegin-tsandend-tsfields

The crux ofthis approach is to use the transactions’ identifiers (Tid) to pre-compute their serialization order. In addition to the fields describedin Sect. 2.2, the version headers also contain the identifier of the lasttransaction that read it (read-ts). The DBMS aborts a transactionthat attempts to read or update a version whose write lock is held byanother transaction.

Existing approachesto provide serializable transaction processing use either (1) addi-tional latches in the index [35, 44] or (2) extra validation steps whentransactions commit [27].

Every DBMS includes aconcurrency control protocolthat coor-dinates the execution of concurrent transactions [11]. This protocoldetermines (1) whether to allow a transaction to access or modify aparticular tuple version in the database at runtime, and (2) whether toallow a transaction to commit its modifications.

Tuples:As shown in Fig. 1, each physical version contains fourmeta-data fields in its header that the DBMS uses to coordinatethe execution of concurrent transactions (some of the concurrencycontrol protocols discussed in the next section include additionalfields). Thetxn-idfield serves as the version’s write lock. Everytuple has this field set to zero when the tuple is not write-locked.Most DBMSs use a 64-bittxn-idso that it can use a single compare-and-swap (CaS) instruction to atomically update the value. If atransactionTwith identifierTidwants to update a tupleA, then theDBMS checks whetherA’stxn-idfield is zero. If it is, then DBMSwill set the value oftxn-idtoTidusing a CaS instruction [27, 44].begin-tscolumnsContentHeadertxn-idend-ts...pointerFigure 1: Tuple Format– The basic layout of a physical version of a tuple.Any transaction that attempts to updateAis aborted if thistxn-idfield is neither zero or not equal to itsTid. The next two meta-datafields are thebegin-tsandend-tstimestamps that represent thelifetime of the tuple version. Both fields are initially set to zero. TheDBMS sets a tuple’sbegin-tstoINFwhen the transaction deletesit. The last meta-data field is thepointerthat stores the address ofthe neighboring (previous or next) version (if any)

Transactions:The DBMS assigns a transactionTa unique,monotonically increasing timestamp as its identifier (Tid) whenthey first enter the system. The concurrency control protocols usethis identifier to mark the tuple versions that a transaction accesses.Some protocols also use it for the serialization order of transactions

Foremost is that it canpotentially allow for greater concurrency than a single-version sys-tem.

This is especially true for in-memory DBMSswhere disk is no longer the main bottleneck

A transaction management scheme permits end-users to access adatabase in a multi-programmed fashion while preserving the illu-

this previous work does not reflect recent trends in latch-free [27] and serializable [20] concurrency control, as well as in-memory storage [36] and hybrid workloads [40]

Multi-versioning allows read-only transactionsto access older versions of tuples without preventing read-writetransactions from simultaneously generating newer versions.

but almost every MVCC DBMS uses tuples because itprovides a good balance between parallelism versus the overheadof version tracking

Thebasic idea of MVCC is that the DBMS maintains multiple physicalversions of each logical object in the database to allow operations onthe same object to proceed in parallel.

le « devenir-animal » de l’humain

devenir humain

visualization application from Tufts called VUE,

In a simple linear regression model, we model the relationship between both variables by a straight line, formally

Job says: “The ear trieth words, as the mouth tasteth meat.

the universe, including man and his divine Principle, is harmonious and eternal.

1. God is All in all. 2. God is good. Good is Mind. 3. God, Spirit, being all, nothing is matter. 4. Life, God, omnipotent Good, deny death, evil, sin, disease. — Disease, sin, evil, death, deny Good, omnipotent God, Life.

The vital part, the heart and Soul of Christian Science, is Love.

there is no pain in Truth, and no truth Inversions. in pain; no nerve in Mind, and no mind in nerve; no matter in Mind, and no mind in matter; no matter in Life, and no life in matter; no matter in Good, and no good in matter.

The Principle of Divine Metaphysics is God; its practice is the power of Truth over error; its rules demonstrate Science.

the awful unreality called evil.

omnipotence, omnipresence, omniscience, — Spirit possessing all power, God's allness learned. filling all space, constituting all Science

I knew the Principle of all harmonious Mind-action to be God

the only realities are the divine Mind Scientific evidence. and idea.

this same mind calls matter, thereby shutting out the true sense of Spirit.

the opposite of Truth — called error, sin, sickness, disease, death — is the false testimony of false material sense; that this false sense evolves, in belief, a subjective state of mortal mind, which this same mind calls matter, thereby shutting out the true sense of Spirit.

Life, Truth, and Love are all-powerful and ever-present

Feeling so perpetually the false consciousness that life inheres in the body, yet remembering that God is A divine discontent. really our Life, we may well tremble, in the prospect of those days wherein we must say, “I have no pleasure in them.”

the revelation of Immanuel, the everpresent God

the demonstrable fact that matter possesses neither sensation nor life;

all real Being is in the divine Mind and idea